Aptopadesha in Hinduism are the words of a trustworthy person. Gautama, the founder of the Nyaya School of philosophy, defines sabda (verbal testimony), a source of valid knowledge, as apthopadesha (aptopadesha sabdah – Nyaya Sutra 1.17) Upadesha means verbal instruction or communication. The knowledge of an object through such verbal communication is verbal knowledge. It is this aspect of verbal communication that distinguishes sabda as a pramana (means of valid knowledge) from other pramanas. All verbal knowledge, however, is not valid. For instance, the deceptive sentences of a scoundrel are not valid. To differentiate valid verbal knowledge from a non-valid one, the adjective apta is added to upadesha in defining shabda as a pramana in Nyayasutras. An Apta is a person who is trustworthy. Vatsyayana while commenting on Nyaya Sutras, defines apta as one who: Possesses direct and valid knowledge Intends to communicate his knowledge correctly Has the ability to co