The means of valid knowledge

SK 4

Perception, inference, and trustworthy testimony — since [these] comprise the establishment of every means of knowledge — are held to be the pramāṇa (dṛṣṭa, anumāna, āptavacana) (means of valid knowledge), threefold; for the establishment of what is to be known is [accomplished] through a means of knowledge.

SK 5

Perception is the determining of each [sense-]object [as it is grasped]. Inference, declared to be of three kinds, is preceded by [the relation of] the liṅga (mark) and the mark-bearer. Trustworthy testimony is reliable revelation [and reliable report].

SK 6

The cognition of things beyond the senses [comes] from inference based on general [observed] correlation. But what is not established even by that — being [wholly] imperceptible — is established from reliable scriptural tradition.

SK 7

[A thing may go unperceived] from being too far off, from being too near, from injury to the sense-organ, from inattention of the mind, from subtlety, from intervention [of an obstacle], from being overpowered [by something stronger], and from being mingled with what is similar.

SK 8

The non-apprehension of that [unmanifest cause] is due to its subtlety, not to its non-existence; its apprehension is through its effects. And that effect — beginning with mahat / buddhi (the great one) — is both dissimilar to and similar to prakṛti / pradhāna / mūlaprakṛti (nature).