Even the very simple act that we call "seeing a person we know" is in part an intellectual one. We fill the physical appearance of the individual we see with all the notions we have about him, and of the total picture that we form for ourselves, these notions certainly occupy the greater part.
The child narrator relates how his family seem to blinker themselves to Charles Swann, choosing what they want to see instead.
We probably have known instances when our friends see us only as their notions of us, not as ourselves truly.
Charles Swann is obviously a greater man of the world than the family wishes to allow. He is a man with the kind of prestiguous contacts and glamorous acquaintances that you only read about in Le Figaro. Yet, the narrator's grandmother only sees him as the son of their neighbour.
It says something about the inherent tunnel vision of the narrator's family - which admits only that which it is comfortable with, and blinds itself to that which is potentially new, and bigger, if not fuller. Later the narrator tells us about his aunt, who is disturbed if there should be anyone in her small village that she knows nothing about. When that happens, she sends her servant to the grocer (the fount of local gossip apparently) for intellgience.
While I am charmed by the wispy recollections filled with comforts and gentle, familiar pleasures, Combray strikes me as a hermetic society.