All the senses combine to give us intelligent perception. We have a sense of space or depth, even if we know nothing of the science of perspective. We are quickly aware of distortion or deformity, since the appearance does not coincide with what experience has taught us is normal or truthful. Form is registered in the mind, even if we know nothing of anatomy and proportion, so that we recognize a face immediately, though we could not give even a good verbal description of it. Our sense of proportion tells us that this is a child and that a [little person], or this a puppy and that a small dog. Intelligent perception includes a feeling for bulk and contour. We know a swan from a goose, or a goose from a duck. This trait is as well developed in those who look at art as it is in artists. We all as individuals have subconsciously accepted certain effects of light. We know when appearances are consistent with daylight, artificial light, twilight, or bright sunlight. Such perception is part of nature.