In Buddhism, form is one of the Five Aggregates, those being:
- form
- sensation
- conception
- awareness
- descrimination
Specifically, form is the physical portion of a sentient being, as in the physical body and the physical components of the sense organs. As such, the form is in most cases what human beings are given to associate with the self. Buddhism rejects the common-sense notion that this is so, identifying the human form as simply one of many processes present in a human being. That's right- a process. In line with the Buddhist view of impermanence, we are invited to see the body not as it is typically conceived- as a static shell that our spirit inhabits- but rather as an element of ourself that is in constant flux and development. From conception to death, the elements that make up the body undergo constant change, as cells die and are created, the sizes and capabilities of organs change, and as the physical substrate or the rest of the Five Aggregates (the sense organs and the brain) are reshaped and changed.
Form is unique among the Five Aggregates because it alone constitutes the physical structures of the human being. In the Buddhist conception of human life, all the other elements that constitute a human are what we would term intangible, or psychological. Common divisions of the Five Aggregates place form at one end and the other elements at the other.
The Buddha said that there were two common attitudes among those who believed there to be a permanent self (atman): those who regarded it as the body, and those who regarded it as the mind. Of the two, he said that the belief that the self was the mind was more dangerous, because it was more difficult to uproot, and more likely to cause suffering. The gross changes that the human form undergoes as it lives, develops, decays, and dies are easier to reference in illustration of the impermanence of the self than are the myriad, more subtle changes that take place in the mind every day. But the deep interpenetration of the physical and the mental means that the ongoing changes in any mental self would have to parallel those that take place in a theorized physical self. Thus, the changes that the body undergoes provide significant evidence for the unviability of a theory that places a permanent self within the environs, physical or psychological, of the human body.