systematic unity into your knowledge, by pursuing an idea of this character—a foundation which is arbitrarily admitted to be ultimate; while the other warns you to consider no individual determination, concerning the existence of things, as such an ultimate foundation, that is, as absolutely necessary, but to keep the way always open for further progress in the deduction, and to treat every determination as determined by some other. But if all that we perceive must be regarded as conditionally necessary, it is impossible that anything which is empirically given should be absolutely necessary.
It follows from this that you must accept the absolutely necessary as out of and beyond the world, inasmuch as it is useful only as a principle of the highest possible unity in experience, and you cannot discover any such necessary existence in the would, the second rule requiring you to regard all empirical causes of unity as themselves deduced.
The philosophers of antiquity regarded all the forms of nature as contingent; while matter was considered by them, in accordance with the judgement of the common reason of mankind, as primal and necessary. But if they had regarded matter, not relatively—as the substratum of phenomena, but absolutely and in itself—as an independent existence, this idea of absolute necessity would have immediately disappeared. For there is nothing absolutely connecting reason with such an existence; on the contrary, it can annihilate it in thought, always and without self-contradiction. But in thought alone lay the idea of absolute necessity. A regulative principle must, therefore, have been at the foundation of this opinion. In fact, extension and impenetrability—which together constitute our conception of matter—form the supreme empirical principle of the unity of phenomena, and this principle, in so far as it is empirically unconditioned, possesses the property of a regulative principle. But, as every determination of matter which constitutes what is real in it—and consequently impenetrability—is an effect, which must have a cause, and is for this reason always derived, the notion of matter cannot harmonize with the idea of a necessary being, in its character of the principle of all derived unity. For every one of its real properties, being derived, must be only conditionally necessary, and can therefore be annihilated in thought; and thus the whole existence of matter can be so annihilated or
