The form, sensation, perception, and formation aggregates (skandhas) are four of the five aggregates. The form aggregate refers to our physical body. Sensation refers to one’s perception and environmental experience. At a coarse level, the perception aggregate refers to what we want to do. The more subtle level of the perception aggregate refers to knowing or awareness: knowing the environment, knowing the current states and sense-objects, etc. The formation aggregate includes physical, verbal, and mental formations (acts).