And now I propose, since an extensive structure cannot be judged of as a whole from a hurried glance, to test it piece by piece from its foundations, so thereby the present Prolegomena may fitly be used as a general outline with which the work itself may occasionally be compared. This notion, if it were founded on nothing more than my conceit of importance, such as vanity commonly attributes to one's own productions, would be immodest and would deserve to be repudiated with disgust. But now, the interests of speculative philosophy have arrived at the point of total extinction, while human reason hangs upon them with inextinguishable affection, and only after having been ceaselessly deceived does it vainly attempt to change this into indifference. In our thinking age it is not to be supposed but that many deserving men would use any good opportunity of working for the common interest of the more and more enlightened reason, if there were only some hope of attaining the goal. Mathematics, natural science, laws, arts, even morality, etc., do not completely fill the soul; there is always a space left over, reserved for pure and speculative reason, the vacuity of which prompts us to seek in vagaries, buffooneries, and myticism for what seems to be employment and entertainment, but what actually is mere pastime; in order to deaden the troublesome voice of reason, which in accordance with its nature requires something that can satisfy it, and not merely subserve other ends or the interests of our inclinations. A consideration, therefore, which is concerned only with reason as it exists for it itself, has as I may reasonably suppose a great fascination for every one who has attempted thus to extend his conceptions, and I may even say a greater than any other theoretical branch of knowledge, for which he would not willingly exchange it, because here all other cognitions, and even purposes, must meet and unite themselves in a whole. I offer, therefore, these Prolegomena as a sketch and text-book for this investigation, and not the work itself. Although I am even now perfectly satisfied with the latter as far as contents, order, and mode of presentation, and the care that I have expended in weighing and testing every sentence before writing it down, are concerned (for it has taken me years to satisfy myself fully, not only as regards the whole, but in some cases even as to the sources of one particular proposition); yet I am not quite satisfied with my exposition in some sections of the doctrine of elements, as for instance in the deduction of the conceptions of the Understanding, or in that on the paralogisms of pure reason, because a certain diffuseness takes away from their clearness, and in place of them, what is here said in the Prolegomena respecting these sections, may be made the basis of the test.