"Direct perception, inference and revealed authority are the three categories of the

called valid proof,

." Swami Veda Bharati

: The

called

, valid proof, concern correct knowledge of a thing that exists in reality, and include cognition derived from direct perception,

where the mind contacts an external object by way of the senses which it had not encountered previously, inference,

, where cognition is derived from a logical thought process, and testimony,

, where cognition is derived from hearing the words of a reliable person.