Building the Aggregate of Form

T1606 explains "constructed" (所造) through five kinds of causal relationship the great elements bear to everything built from them: the great elements are the generative cause (nothing constructed can arise apart from them), the supporting cause (constructed form has no capacity to stand on its own, occupying its own distinct location), the establishing cause (constructed form varies precisely as the great elements it depends on vary), the sustaining cause (constructed form continues in an unbroken, similar succession only because the great elements sustain it), and the nurturing cause (the great elements are what allow constructed form to grow). One classical point worth flagging for later: the "pure, translucent form" that each physical faculty is defined as is not the visible eyeball, ear, or the like, but a subtler, imperceptible form seated within it — what later Abhidharma literature calls the faculty's own "net-form," distinct from the flesh-form anyone can see.

T1606 sorts these twenty-five into six causal groupings — a characteristic mark shared by four items, a way of designating boundaries shared by ten, an effect of benefit or harm shared by eight, and three single-item categories each established on its own distinct ground (as a basis for something else, as a mark in its own right, and as an ornament). It also glosses two of the more obscure terms: "distant space-form" (逈色) is form perceived at a distance, free of any obstruction by a nearer object; "the single hue of open space" (空一顯色) is simply the color one sees when looking at open sky above — blue, in ordinary daylight, but named generically to cover whatever hue empty space itself presents.

For sound, T1606 glosses "caused by great elements that are part of a living body" as speech and the like, and "not part of a living body" as the sound of a tree or a river; "conventionally established" is ordinary colloquial speech, "brought about by realization" is what a noble one says, and "arising from mere conceptual construction" is what outsiders to the teaching say. For smell and taste, "innate" means a smell or taste already present in a substance by nature (sandalwood is T1606's example for innate smell), "produced by mixture" means a blend of substances such as incense, and "produced by transformation" means the smell or taste a substance takes on once it has ripened or spoiled, as in ripened fruit.

T1606 calls this "one portion" of the touched because the touch sense field as a whole also includes the four great elements themselves (solidity, moisture, warmth, and mobility, already given their own definitions above) — this list of twenty-one is specifically the touch-objects constructed from those four elements, not the elements' own bare, defining qualities. It sorts the twenty-one by eight causal grounds and offers brief glosses for the less obvious pairs: stickiness arises when the water and wind elements are imbalanced within a mixture, itching when water and earth are imbalanced; rest, strength, and vigor arise when all four elements are in balance, with "vigor" specifically meaning a fearless steadiness of body; and satiety, unlike the other imbalance-caused sensations, can arise from either an excess or a deficiency of the elements.

T1606 glosses each of the five directly. "Form reduced to its finest analysis" (極略色) is what remains when ordinary visible form is analyzed down to the level of the atom — a purely conceptual limit-point, not something anyone could ever actually perceive. "Form abstracted at a distance" (極逈色) is that same finest-analysis form considered specifically once it is free of any obstructing nearer object, as when a distant mountain range is analyzed the same way. "Form drawn forth by the precept a monastic undertakes" (受所引色) is what later Abhidharma calls unmanifest form (無表色) — the subtle, ongoing moral potency generated by taking a monastic vow, which persists even while the monastic is asleep or otherwise not actively doing anything virtuous. "Form arising from conceptual construction" (遍計所起) is the mere image present in an unreliable, non-veridical act of imagination — a mental picture with no corresponding external object at all. And "form produced by mastery in concentration" (色定自在所生色) is the form that an accomplished meditator, through mastery of concentration, can freely bring into being or transform at will — a capacity discussed further when the treatise later takes up the higher trainings.