Yoga Sutra 4.17 according to whether the mind is coloured by it, a thing is known or unknown

Sūtra IV.17

According to whether the mind is coloured by it, a thing is known or unknown

According to whether that object causes a colouring of the mind corresponding to its existence, the thing is known or unknown. By whatever thing mind is coloured, that thing is known; by whatever thing it is not so coloured, that is unknown. And this colouring corresponds to a change of the mind. For mind is changed into the outer form when conjoined with that, through the channel of the senses.

As to what causes the change, he says:

The objects are comparable to a magnet like a magnet, and the mind corresponds to iron, being like iron in that when the object is near it, it is affected. The similarity of the object to a magnet is from its power to affect the mind simply by being near it. Thus the object draws to itself and colours the mind, which is changed into the form of the object.

By whatever object the mind is coloured, that object is known, and furthermore, another object, which does not colour the mind, is unknown.

So From the fact that its objects have the character of being known and also not known, the mind must be changeable. Here again, for one who maintains that the object is purely dependent on the mind, or else that it is mind itself, there will be either omniscience or else no knowledge of objects at all. For without knowledge, mind would not exist. But we do not find this, but rather that objects of the mind are known and also unknown. So there must be changeability of the mind, since its objects are not in a fixed state; and otherwise, relation with them is not feasible.

But to Him, Puruṣa its Lord, the experiencer, that very mind whose objects are known and unknown is the object in the form of a mental process, for mind with its mental processes inhibited would not be an object.