The Absorbent Mind
"The child must possess within himself, from birth, a capacity - only a potential at first - of abstracting or taking off from particular things their essential qualities. If you watch carefully any small child, of one to two years old, you will see that he is not only interested in objects as a whole, but also in their qualities, such as roughness, smoothness, hardness, softness, colour, taste, texture, weight, pliability, and so on."
Maria Montessori: Her Life and Work