大乘起信論廣釋卷第三．四．五 4.120

4.120

論。以對色故至虛空之相　釋曰。此釋也。以對色等者。初明情有。以對礙色故。於無礙明闇之處說有虛空。然此乃至空界之色。而是眼識所行境界。牽起念念分別之心。故言以對色故有。今心生滅等以一切等者。後顯理無。本以對色而立虛空色。體當無。寧有空相。

[Treatise:] Because of contrasting with form, [... the mark of empty space].
[Commentary:] This is the explanation. 'Because of contrasting with form, and so forth': this first clarifies existence in conception. Because of contrasting with obstructive form, empty space is spoken of in unobstructed places of light and dark. However, this is even the form of the realm of space, which is an objective sphere traversed by the eye-consciousness, inducing a mind of conceptualization moment by moment; hence it says 'existing because of contrasting with form'. 'Now mind arising and ceasing, and so forth, because all, and so forth': this subsequently reveals non-existence in principle. Originally, empty space was established in contrast to form; when the substance of form is inherently non-existent, how could there be a mark of space?