Whatever the thing in itself may be, Kant rightly concluded that time, space and causality are not determinations of it but belong only to its appearance

The passage

Whatever the thing in itself may be, Kant rightly concluded that time, space and causality are not determinations of it, but could attach to it only after and in so far as it has become representation, that is, belong only to its appearance, not to it itself.

The first sentence of the second paragraph of § 24. It names Kant, calls his conclusion right and asserts it, under »Was auch immer das Ding an sich sei«, which the statement keeps. Kant's own statement of it for space is A 26 / B 42, »Der Raum stellt gar keine Eigenschaft irgend einiger Dinge an sich ... vor, d. i. keine Bestimmung derselben« (c-kant-space-not-of-things-in-themselves); Schopenhauer's word is the same, »nicht Bestimmungen desselben«, and the link shares_premise_with is set between the two on the part about space, named in the comparison x-thing-in-itself as the premise that space is no determination of the thing in itself. The Schopenhauer statement asserts more: time and causality too, and that the forms attach to the thing in itself only once it has become representation. The sentences that follow give the ground, »Denn da das Subjekt sie aus sich selbst ... vollständig erkennt und konstruirt«, not formalized; § 23 states the doctrine (c-schopenhauer-will-free-of-forms-of-appearance), where the earlier link is set, and a page later calls it »den Sinn der Kantischen Lehre« (c-schopenhauer-will-groundless-and-one).