The term "Pad?rtha" derived from two "Pada" or word and "Artha" or the meaning or referent. Therefore etymologically the term Pad?rtha means "the meaning or referent of words".
Almost all the philosophical systems of India accept liberation as the ultimate goal of life; it is the summum bonum. For attaining liberation different philosophies prescribe different means. According to Gautama, liberation can be attained by the true knowledge of the categories or pad?rthas. According to the Vaisheshika school, all things which exist, which can be cognised, and which can be named are pad?rthas (literal meaning: the meaning of a word), the objects of experience.
Later Vai?e?ikas like, ?r?dhara and Udayana and ?iv?ditya added one more category abhava which means non-existence.
The Ny?ya metaphysics recognizes sixteen padarthas or categories and includes all six (or seven) categories of the Vai?e?ika in the second one of them, called prameya. These are:
The Vai?e?ika categories or Pad?rthas are separate from the categories of Aristotle, Kant and Hegel. According to Aristotle, categories are logical classification of predicates; Kant states that categories are only patterns of the understanding and Hegel's categories are dynamic stages in the development of thought, but the Vai?e?ika categories are metaphysical classification of all knowable objects. Aristotle accepts ten categories: 1. Substance, 2. Quality, 3. Quantity, 4. Relation, 5 Place, 6. Time, 7. Posture, 8. Property, 9. Activity, and 10. Passivity. The Vai?e?ikas instead place the concepts of time and place under substance; relation under quality; inherence, quantity and property under quality. Passivity is considered the opposite of activity. Gautama enumerates sixteen Pad?rthas.