I think what Donuel is driving at is that our responses are conditioned by the world around us to some extent.

If someone perceives, on a regular basis, that a specific group of people are not in some way acceptable, or are "lessor" in some way, that person, unless they are very careful, will in time begin to perceive that group in the same way.

We owe to it ourselves to be constantly on guard against this, because if we succumb we become less.