Critique of Judgement by Immanuel Kant Chapter 57 Page 17

Remark II.

The following important remark occurs here: There are three kinds of Antinomies of pure Reason, which, however, all agree in this, that they compel us to give up the otherwise very natural hypothesis that objects of sense are things in themselves, and force us to regard them merely as phenomena, and to supply to them an intelligible substrate (something supersensible of which the concept is only an Idea, and supplies no proper knowledge). Without such antinomies Reason could never decide upon accepting a principle narrowing so much the field of its speculation, and could never bring itself to sacrifices by which so many otherwise brilliant hopes must disappear. For even now when, by way of compensation for these losses, a greater field in a practical aspect opens out before it, it appears