1. All living organisms are composed of one or more cells. This means that cells are the basic building blocks of life, and all living things are made up of them. This was a revolutionary concept that shifted our understanding of life from a holistic view to a cellular one.

2. The cell is the basic unit of structure and function in living organisms. This means that cells are not just the building blocks of life, but they are also the functional units. All the processes of life, from metabolism to reproduction, happen at the cellular level.

3. All cells arise from pre-existing cells. This means that cells do not spontaneously generate, but instead are always produced by the division of other cells. This principle emphasizes the continuity of life and the importance of cell division in the growth and development of organisms.