俱舍論疏 1.177

1.177

論「柔軟名滑至翻此為輕」，第二當體立名也。問：何故七種觸中唯滑等四觸言性，餘觸及餘境不說性耶？答：此為對後三從果立名故。此四從自性為名，故為性也；後三從果為名，故不言性。餘境無相對故，所以不名為性。「可稱名重」者，謂能牽秤向下。不可稱者，謂不能牽秤向下，及有力上昇，如煙、炎等皆名為輕。餘文可解。

[Regarding the] treatise's [statement]: "Softness is called smooth […] the reverse of this is light": the second [part] establishes names based on their intrinsic nature. Question: Why among the seven kinds of tangible do only the four tangibles such as smoothness speak of nature (性), while the remaining tangibles and the remaining sense-objects do not speak of nature? Answer: This is in contrast to the latter three, which are named after their results. Because these four are named from their self-nature, they are [designated as] nature; because the latter three are named from their results, they do not speak of nature. The other sense-objects have no such contrast, and therefore are not called nature. "Weighable is called heavy" means able to draw the scale downward. Unweighable means unable to draw the scale downward, and possessing the force to rise upward, such as smoke, flame, and so forth, which are all called light. The rest of the text is easy to understand.