"O yes," my father said, "He existed even a hundred years ago."
"Then perhaps," I continued, "God is already a thousand years old?"
"Silence! God was eternal."
"But," I insisted, "He must surely have been born at some time."
"You little fool," said my father, "No! He was for ever and ever and ever."
With this answer I was not indeed satisfied; but I thought "Surely papa must know better than I, and with that I must therefore be content."
This mode of representation is very natural in early youth, when the understanding is still undeveloped, while the imagination is in full bloom. The understanding seeks merely to grasp, the imagination to grasp all round.[13] That is to say, the understanding seeks to make the origin of an object conceivable, without considering, whether the object, whose origin is known, can also be actually represented by us or not. The imagination, on the other hand, seeks to gather into a complete image something, the origin of which is to us unknown. Thus, for example, an infinite series of numbers, which progresses according to a definite law, is for the understanding an object, to which by this law definite qualities are attached, and an object just as good as a finite series, which progresses according to the same law. For the imagination, on the other hand, the latter indeed is an object; but not the former, because it cannot grasp the former as a completed whole.
A long time afterwards, when I was staying in Breslau, this consideration suggested to me a thought, which I expressed in an essay that I laid before Professor Garve, and which, though at the time I knew nothing of the Kantian philosophy, still constitutes its foundation. I explained this somewhat in the following way:—The metaphysicians necessarily fall into self-contradiction. According to the confession of Leibnitz himself, who in this appeals to the experiment of Archimedes with the lever, the Law of Sufficient Reason or Causality is a principle of experience. Now, it is quite true that in experience everything is found to have a cause; but for the very reason, that every thing has a cause, nothing can be met with in experience which is a first cause, that is, a cause which has no cause to itself. How then can the metaphysicians infer from this law the existence of a first cause?
Afterwards I found this objection more particularly developed in the Kantian philosophy, where it is shown that the Category of Cause, or the form of hypothetical judgments used in reference to the objects of nature, by which their relation to one another is determined a priori, can be applied only to objects of experience through an a priori schema. The first cause, which implies a complete infinite series of causes, and therefore in fact a contradiction, since the infinite can never be complete, is not an object of the understanding, but an idea of reason, or, according to my theory, a fiction of the imagination, which, not content with the mere knowledge of the law, seeks to gather the multiplicity, which is subject to the law, into an image, though in opposition to the law itself.