A mask presents a unique concentration of sense organs: sight, smell, taste, touch, hearing. A mask becomes alive when its senses appear to be actively engaged in exploring its environment.
There is strong evidence to support the contention that the recognition of the mask is hard-wired into our biology. New-born babies are searching for the human face and registering changes in facial emotions within hours of birth. There are very specific conditions such as prosopagnosia and "super recognition" related to facial recognition. If one stares into the eyes of an upside-down human face one experiences a kind of disorienting "jump" in one's visual perception, rather like that one experiences in certain optical illusions. Suddenly it is not a human face at all, but a kind of monster from outer space.
One should treat a mask with the same respect that one gives to a real human face, handling it gently, not putting it down on the floor or a chair, not poking one's fingers into the eyes.
A mask should be larger than the human face. Or smaller, like the Japanese Noh.
There is a resonance (perhaps one might even say a sacred dimension) to the mask that is very similar to the Buddhist prayer flags and temple prayer wheels that are found in Tibet. Every time the flag flaps in the wind, the prayer written upon it flies off to the gods. Every spin of the prayer wheel reorders the universe. There is nothing moralistic going on here!