The first cognition is merely sensation: sensation and the remembrance of sensation being the first element in all knowing and in all conception.
The circuit of touch, taste, and smell must be well established, before the eyes begin actually to see.

All mental knowledge is built up of sensation and of memory.

It is the continually recurring sensation of the touch of the mother which forms the basis of the first conception of the mother.

After that, the gradually discriminated taste of the mother, and scent of the mother.

Till gradually sight and hearing develop and largely usurp the first three senses, as medium of correspondence and of knowledge.
And while, of course, the sensational _knowledge_ is being secreted in the brain, in some much more mysterious way the living individuality of the child is being developed in the four first nuclei, the four great nerve-centers of the primary field of consciousness and being.
As time goes on, the child learns to see the mother.