In Vaisheshika philosophy, Guna or quality is defined as that which inheres in substance, does not contain a quality itself, and is not an independent cause of samyoga (conjunction) and vibhaga (disjunction).
It is to be noted that the definition of quality it is denied that a quality can possess further quality. The aim of this part of the definition is to avoid inconsistency with the definition of substance already given, which admits that substance is only that in which qualities and activities inhere. Consequently, it now logically required to maintain that quality cannot inhere in a quality. That a quality cannot be an independent cause of conjunction and disjunction does not deny that a quality can be a non-material cause of a thing. The color of the threads is the non-material cause of the color of the cloth.
Vaisheshika philosophy enumerates 17 qualities: color, taste, smell, touch, number, measure, separateness, conjunction, disjunction, priority, posteriority, knowledge, pleasure, pain, desire, aversion and effort. To this list Prasatapada adds seven more, as follows, weight, fluidity, viscidity, virtue, vice, sound and tendency.
Of these, some, such as color, taste, smell, touch, fluidity, and viscidity, are qualities of corporeal substances; some, such as knowledge, pleasure, pain, desire, aversion, effort, virtue and vice, are qualities of incorporeal substances. Conjunction, disjunction, individuality or separateness, etc., inhere in more substances than one, and the rest inhere in single substances. Some of the qualities, such as sound, touch, color, taste and smell, are perceptible by the external senses separately; and some other ones, such as number, size, individuality or separateness, conjunction, disjunction, priority, posteriority, fluidity, and viscidity, etc, are perceptible by two senses.
Knowledge, pleasure, pain, desire, aversion and effort are perceptible by the internal sense organ (manas); while virtue, vice, and a tendency called mental impression, which enable us to remember, and weight are not open to perception at all.
Some of the qualities, such as number size, separateness, conjunction, disjunction, priority, posteriority, weight, caused fluidity, and a kind of tendency called velocity, are general qualities, while color, taste, smell, touch, viscidity, constitutional or natural fluidity, knowledge, pleasure, pain, desire, aversion, effort, virtue, vice, tendency and sound are special qualities which help to distinguish substances which possess them from others.