“So how do you find out these important facts?
According to Patañjali an object which can be understood by the mind
can be perceived in three ways Pratyakṣa, Anumāna, Āgamā:
Pratyakṣa (through the senses) – Direct perception
In other words the object placed in front of you.
The senses help us in comprehending the object.
Anumāna (inference) – We don’t have all the information.
We have certain indications that allow us to complete the picture.
Anu – to follow.
From the part you can get the whole.
From the effect you get to the cause.
Āgamā (authentic teachings) – No information directly.
Only information is from words
Some truth that has already existed.
We take the words and believe them as if we had seen it for ourselves.
For example God.
Patañjali has proposed three approaches or systems to verify the indications.”
– TKV Desikachar France 1983

“The means to knowledge
i.e. our method of knowing (Pramāṇa – right perception), involves a progression,
a movement from Āgama (authentic teachings),
what we hear or perceive or learn from authoritative sources;
to Pratyakṣa (through the senses) to see the fire, itself, the fact, the truth, the reality.
Such a means to know is a movement from the gross to the subtle.
In Vikalpa, we don’t have this progression.”
– TKV Desikachar Madras December 19th 1988