As a result, apples necessarily possess certain features common to all things that fall under these genera. One of these features, science has discovered, is mass; which in turn means that these things are affected by gravity. Therefore, an apple qua material, living thing has, by necessity, the potential to be attracted to another body. This is the answer classical philosophy would provide to the question, “Why do apples fall to the ground?”. While science is needed to describe how mass and gravity work, it can never tell us why apples are one way rather than another. Only metaphysics can explain the nature of an apple. The “Why?” question, then, is clearly necessary if we are to obtain complete knowledge of anything.