It must be *possible* for the *I think* to accompany all my representations: for otherwise something would be represented within me that could not be thought at all, in other words, the representation would either be impossible, or at least would be nothing to me. That representation which can be given prior to all thought is called *intuition*, and all the manifold of intuition has, therefore, a necessary relation to the *I think* in the same subject in which this manifold of intuition is found. This representation (the *I think*), however, is an act of *spontaneity*, that is, it cannot be considered as belonging to sensibility. I call it *pure apperception*, in order to distinguish it from empirical apperception, as also from original apperception, because it is that self-consciousness which, by producing the representations, *I think* (which must be capable of accompanying all other representations, and which is one and the same in all consciousness), cannot itself be accompanied by any further representations. I also call the unity of apperception the *transcendental* unity of self-consciousness, in order to indicate that *a priori* knowledge can be obtained from it. For the manifold representations given in an intuition would not one and all be *my* representations, if they did not all belong to one self-consciousness. What I mean is that, as my representations (even though I am not conscious of them as that), they must conform to the condition under which alone they *can* stand together in one universal self-consciousness, because otherwise they would not one and all belong to me. From this original combination much can be inferred.The thoroughgoing identity of the apperception of a manifold that is given in intuition contains a synthesis of representations, and is possible only through the consciousness of this synthesis. For the empirical consciousness which accompanies different representations is itself dispersed and without reference to the identity of the subject. Such a reference comes about, not simply through my accompanying every representation with consciousness, but through my *adding* one representation to another and being conscious of the synthesis of them. Only because I am able to combine a manifold of given representations *in one consciousness* is it possible for me to represent to myself the *identity of the consciousness in these representations*, that is, only under the presupposition of some *synthetic* unity of apperception is the *analytic* unity of apperception possible. The thought that the representations given in intuition belong one and all *to me*, is therefore the same as the thought that I unite them in one self-consciousness, or can at least do so; and although that thought itself is not yet the consciousness of the synthesis of representations, it nevertheless presupposes the possibility of this synthesis. In other words, it is only because I am able to comprehend the manifold of representations in one consciousness that I call them one and all *my* representations. For otherwise I should have as many-coloured and varied a self as I have representations of which I am conscious. Synthetic unity of the manifold of intuitions, as given *a priori*, is thus the ground of the identity of apperception itself, which precedes *a priori* all *my* determinate thought. Combination, however, does not lie in the objects, and cannot be borrowed from them by perception and thus first be taken into the understanding. It is, rather, solely an act of the understanding, which itself is nothing but the faculty of combining *a priori* and of bringing the manifold of given representations under the unity of apperception; and the principle of this unity is, in fact, the supreme principle of all human knowledge."—from_Critique of Pure Reason_. Translated, edited, and with an Introduction by Marcus Weigelt, based on the translation by Max Müller, pp. 124-128
In consequence of the inevitably scattered and fragmentary nature of our thinking, which has been mentioned, and of the mixing together of the most heterogeneous representations thus brought about and inherent even in the noblest human mind, we really possess only *half a consciousness*. With this we grope about in the labyrinth of our life and in the obscurity of our investigations; bright moments illuminate our path like flashes of lighting. But what is to be expected generally from heads of which even the wisest is every night the playground of the strangest and most senseless dreams, and has to take up its meditations again on emerging from these dreams? Obviously a consciousness subject to such great limitations is little fitted to explore and fathom the riddle of the world; and to beings of a higher order, whose intellect did not have time as its form, and whose thinking therefore had true completeness and unity, such an endeavor would necessarily appear strange and pitiable. In fact, it is a wonder that we are not completely confused by the extremely heterogeneous mixture of fragments of representations and of ideas of every kind which are constantly crossing one another in our heads, but that we are always able to find our way again, and to adapt and adjust everything. Obviously there must exist a simple thread on which everything is arranged side by side: but what is this? Memory alone is not enough, since it has essential limitations of which I shall shortly speak; moreover, it is extremely imperfect and treacherous. The *logical ego*, or even the *transcendental synthetic unity of apperception*, are expressions and explanations that will not readily serve to make the matter comprehensible; on the contrary, it will occur to many that“Your wards are deftly wrought, but drive no bolts asunder.”Kant’s proposition: “The *I think* must accompany all our representations ,” is insufficient; for the “I” is an unknown quantity, in other words, it is itself a mystery and a secret. What gives unity and sequence to consciousness, since by pervading all the representations of consciousness, it is its substratum, its permanent supporter, cannot itself be conditioned by consciousness, and therefore cannot be a representation. On the contrary, it must be the *prius* of consciousness, and the root of the tree of which consciousness is the fruit. This, I say, is the *will*; it alone is unalterable and absolutely identical, and has brought forth consciousness for its own ends. It is therefore the will that gives unity and holds all its representations and ideas together, accompanying them, as it were, like a continuous ground-bass. Without it the intellect would have no more unity of consciousness than has a mirror, in which now one thing now another presents itself in succession, or at most only as much as a convex mirror has, whose rays converge at an imaginary point behind its surface. But it is *the will* alone that is permanent and unchangeable in consciousness. It is the will that holds all ideas and representations together as means to its ends, tinges them with the colour of its character, its mood, and its interest, commands the attention, and holds the thread of motives in its hand. The influence of these motives ultimately puts into action memory and the association of ideas. Fundamentally it is the will that is spoken of whenever “I” occurs in a judgement. Therefore, the will is the true and ultimate point of unity of consciousness, and the bond of all its functions and acts. It does not, however, itself belong to the intellect, but is only its root, origin, and controller."—from_The World as Will and Representation_. Translated from the German by E. F. J. Payne in two volumes: volume II, pp. 139-140
Ontically, of course, Dasein is not only close to us―even that which is closest: we *are* it, each of us, we ourselves. In spite of this, or rather for just this reason, it is ontologically that which is farthest. To be sure, its ownmost Being is such that it has an understanding of that Being, and already maintains itself in each case as if its Being has been interpreted in some manner. But we are certainly not saying that when Dasein's own Being is thus interpreted pre-ontologically in the way which lies closest, this interpretation can be taken over as an appropriate clue, as if this way of understanding Being is what must emerge when one's ownmost state of Being is considered as an ontological theme. The kind of Being which belongs to Dasein is rather such that, in understanding its own Being, it has a tendency to do so in terms of that entity towards which it comports itself proximally and in a way which is essentially constant―in terms of the 'world'. In Dasein itself, and therefore in its own understanding of Being, the way the world is understood is, as we shall show, reflected back ontologically upon the way in which Dasein itself gets interpreted.Thus because Dasein is ontico-ontologically prior, its own specific state of Being (if we understand this in the sense of Dasein's 'categorial structure') remains concealed from it. Dasein is ontically 'closest' to itself and ontologically farthest; but pre-ontologically it is surely not a stranger."―from_Being and Time_. Translated by John Macquarrie & Edward Robinson, pp. 36-37
The *second task* consists in distinguishing the mode of knowing operative in ontology as science of Being, and this requires us to *work out the methodological structure of ontological-transcendental differentiation*. In early antiquity it was already seen that Being and its attributes in a certain way underlie beings and precede them and so are *a proteron*, an earlier. The term denoting this character by which Being precedes beings is the expression *a priori*, *apriority*, being earlier or prior. As *a priori*, Being is earlier than beings. The meaning of this *a priori*, the sense of the earlier and its possibility, has never been cleared up. The question has not even once been raised as to why the determinations of Being and Being itself must have this character of priority and how such priority is possible. To be earlier is a determination of time, but it does not pertain to the temporal order of the time that we measure by the clock; rather, it is an earlier that belongs to the "inverted world." Therefore, this earlier which characterises Being is taken by the popular understanding to be the later. Only the interpretation of Being by way of temporality can make clear why and how this feature of being earlier, apriority, goes together with Being. The *a priori* character of Being and of all the structures of Being accordingly calls for a specific kind of approach and way of apprehending Being―*a priori cognition*.The basic components of *a priori* cognition constitute what we call *phenomenology*. Phenomenology is the name for the method of ontology, that is, of scientific philosophy. Rightly conceived, phenomenology is the concept of a method. It is therefore precluded from the start that phenomenology should pronounce any theses about Being which have specific content, thus adopting a so-called standpoint." ―Martin Heidegger, from_The Basic Problems of Phenomenology_
Because they are assertions about Being in the light of time properly understood, all ontological propositions are Temporal propositions. It is only because ontological propositions are Temporal propositions that they can and must be *a priori propositions*. It is only because ontology is a Temporal science that something like the *a priori* appears in it. *A priori* means "from the earlier" or "the earlier." "*Earlier*" is patently a *time-determination*. If we have been observant, it must have occurred to us that in our explications we employed no word more frequently than the expression "already." It "already antecedently" lies at the ground: "it must always already be understood beforehand": where beings are encountered, Being has "already beforehand" been projected. In using all of these temporal, really Temporal, terms we have in mind something that the tradition since Plato calls the *a priori*, even if it may not use the very term itself. In the preface to his *Metaphysische Anfangsgründe der Naturwissenschaft [Metaphysical principles of natural science], Kant says: "Now to cognize something *a priori* means to cognize it from its mere possibility." Consequently, *a priori* means that which makes beings as beings possible in *what* and *how* they are. But why is this possibility labeled by the term "earlier"? Obviously not because we recognize it earlier than beings. For what we experience first and foremost is beings, that which is; we recognize Being only later or maybe even not at all. This time-determination "earlier" cannot refer to the temporal order given by the common concept of time in the sense of intratemporality. On the other hand, it cannot be denied that a time determination is present in the concept of the *a priori*, the earlier. But, because it is not seen how the interpretation of Being necessarily occurs in the horizon of time, the effort has to be made to explain away the time determination by means of the *a priori*. Some go so far as to say that the *a priori*―the essentialities, the determination of beings in their Being―is extratemporal, supratemporal, timeless. That which does the enabling, the possibilities are characterized by a time-determination, the earlier, because in this *a priori* nothing of time is supposed to be present, hence *locus a non lucendo*? Believe it if you wish."―from_The Basic Problems of Phenomenology_
On the other hand, it is also characteristic of the state of philosophical inquiry today and has been for a long time that, while there has been extensive controversy about whether or not the *a priori* can be known, it has never occurred to the protagonists to ask first what could really have been meant by the fact that a time-determination turns up here and why it must turn up at all. To be sure, as long as we orient ourselves toward the common concept of time we are at an impasse, and negatively it is no less than consistent to deny dogmatically that the *a priori* has anything to do with time. However, time in the sense commonly understood, which is our topic here, is indeed only one derivative, even if legitimate, of the original time, on which the Dasein's ontological constitution is based. *It is only by means of the Temporality of the understanding of Being that it can be explained why the ontological determinations of Being have the character of apriority*. We shall attempt to sketch this briefly, as far as it permits of being done along general lines.We have just seen that all comportment toward beings already understands Being, and not just incidentally: Being must necessarily be understood precursorily (pre-cecently). The possibility of comportment toward beings demands a precursory understanding of Being, and the possibility of the understanding of Being demands in its turn a precursory projection upon time. But where is the final stage of this demand for ever further precursory conditions? It is temporality itself as the basic constitution of the Dasein. Temporality, due to its horizonal-ecstatic nature, makes possible *at once* the understanding of Being and comportment toward beings; therefore, that which does the enabling as well as the enablings themselves, that is, the possibilities in the Kantian sense, are "temporal," that is to say, Temporal, in their specific interconnection. Because the original determinant of possibility, the origin of possibility itself, is time, time temporalizes itself as the absolutely earliest. *Time is earlier than any possible earlier* of whatever sort, because it is the basic condition for an earlier as such. And because time as the source of all enablings (possibilities) is the earliest, all possibilities as such in their possibility-making function have the character of the earlier. That is to say, they are *a priori*. But, from the fact that time is the earliest in the sense of being the possibility of every earlier and of every *a priori* foundational ordering, it does not follow that time is ontically the first being; nor does it follow that time is forever and eternal, quite apart from the impropriety of calling time a being at all.” ―from_The Basic Problems of Phenomenology_
As a method however, the *method of ontology* is nothing but the sequence of the steps involved in the approach to Being as such and the elaboration of its structures. We call this method of ontology *phenomenology*. In more precise language, phenomenological investigation is explicit effort applied to the method of ontology. However, such endeavors, their success or failure, depend primarily, in accordance with our discussion, on how far phenomenology has assured for itself the object of philosophy―how far, in accordance with its own principle, it is unbiased enough in the face of what the things themselves demand. We cannot now enter any further into the essential and fundamental constituent parts of this method. In fact, we have applied it constantly. What we would have to do would be merely to go over the course already pursued, but now with explicit reflection on it. But what is most essential is first of all to have traversed the whole path once, so as, for one thing, to learn to wonder scientifically about the mystery of things and, for another, to banish all illusions, which settle down and nest with particular stubbornness precisely in philosophy.There is no such thing as *the one* phenomenology, and if there could be such a thing it would never become anything like a philosophical technique. For implicit in the essential nature of all genuine method as a path toward the disclosure of objects is the tendency to order itself always toward that which it itself discloses. When a method is genuine and provides access to the objects, it is precisely then that the progress made by following it and the growing originality of the disclosure will cause the very method that was used to become necessarily obsolete. The only thing that is truly new in science and in philosophy is the genuine questioning and struggle with things which is at the service of this questioning." ―from_The Basic Problems of Phenomenology_
From *the form of time and of the single dimension* of the series of representations, on account of which the intellect, in order to take up one thing, must drop everything else, there follows not only the intellect’s distraction, but also its *forgetfulness*. Most of what it has dropped it never takes up again, especially as the taking up again is bound to the principle of sufficient reason, and thus requires an occasion which the association of ideas and motivation have first to provide. Yet this occasion may be the remoter and the smaller, the more our susceptibility to it is enhanced by interest in the subject. But, as I have already shown in the essay *On the Principle of Sufficient Reason*, memory is not a receptacle, but a mere faculty, acquired by practice, of bringing forth any representations at random, so that these have always to be kept in practice by repetition, otherwise they are gradually lost. Accordingly, the knowledge even of the scholarly head exists only *virtualiter* as an acquired practice in producing certain representations. *Actualiter*, on the other hand, it is restricted to one particular representation, and for the moment is conscious of this one alone. Hence there results a strange contrast between what a man knows *potentia* and what he knows *actu*, in other words, between his knowledge and his thinking at any moment. The former is an immense and always somewhat chaotic mass, the latter a single, distinct thought. The relation is like that between the innumerable stars of the heavens and the telescope’s narrow field of vision; it stands out remarkably when, on some occasion, a man wishes to bring to distinct recollection some isolated fact from his knowledge, and time and trouble are required to look for it and pick it out of that chaos. Rapidity in doing this is a special gift, but depends very much on the day and the hour; therefore sometimes memory refuses its service, even in things which, at another time, it has ready at hand. This consideration requires us in our studies to strive after the attainment of correct insight rather than an increase of learning, and to take to heart the fact that the *quality* of knowledge is more important than its quantity. Quantity gives books only thickness; quality imparts thoroughness as well as style; for it is an *intensive* dimension, whereas the other is merely extensive. It consists in the distinctness and completeness of the concepts, together with the purity and accuracy of the knowledge of perception that forms their foundation. Therefore the whole of knowledge in all its parts is permeated by it, and is valuable or troubling accordingly. With a small quantity but good quality of knowledge we achieve more than with a very great quantity but bad quality."—from_The World as Will and Representation_. Translated from the German by E. F. J. Payne in two volumes: volume II, pp. 139-141