133. The understanding is, in its acts, subject to a law of succession, or the idea of time. The same thing obtains in nature, whether it is so verified in reality, or time is considered as a subjective condition which we transfer to objects; be this doctrine of Kant, which we shall in due time examine, as it may, it is certain that succession, at least for us, exists, and that we cannot ignore it. In this hypothesis an infinite evolution can be known to us only in an infinite time. Thus, by a metaphysical necessity, we are unable to know not only the future evolution of the absolute, but also the present and the past. This evolution being absolutely necessary, according to the doctrine to which we have reference, an infinite succession must have preceded us; thus the present organization of the universe must be regarded as one round of an unlimited ladder, which in the past as in the future, has no measure but eternity. We can know the present state of the world solely by observation, and then only to a very limited degree; we must, therefore, of necessity, deduce it from the idea of the absolute, by following it in its infinite evolution. Were this not, however, in itself radically impossible, it would, nevertheless, labor under the inconvenience of being too long a task to be accomplished in the life-time of any one man, or even in that of all men who have ever lived, taken collectively. 134. But let us return to the representation of causality. The ideal representation may be reduced to that of causality; for since a spirit can have no idea of an object not produced by it, unless communicated to it by another spirit, the cause of the thing represented, we infer that all purely ideal representations proceed either directly or indirectly, mediately or immediately, from the cause of the objects known. And since, on the other hand, as we have already seen, the first being knows things distinct from himself only, as he is their cause; we hold the representation of ideality to be reduced to that of causality, thus in part verifying the principle of Vico, the profound Neapolitan thinker: "the intellect only knows what it does." 135. From this doctrine flow two consequences of which we must take note: I. There are only two primitive sources of intellectual representation: identity and causality. That of ideality is necessarily derived from that of causality. II. In the real order, the principle of being is identical with the principle of knowledge. That only which gives being can give knowledge. The first cause can give knowledge only in so far as it gives being: it represents because it causes. 136. The representation of ideality, although connected with that of causality, is yet really distinct from it. The explanation of its nature belongs indeed to the treatise on ideas; but we cannot relinquish, without an illustration, a point so closely connected with the problem of intellectual representation.