Cell theory is the scientific theory that describes the properties of cells, primarily that the cell is the basic unit of life, and all living things are made of cells and all cells come from pre-existing cells. Modern cell theory is the result of centuries of research and experimentation facilitated by the invention of the microscope. Cell theory dispels the past myth of spontaneous generation or life coming from nothing.
Cell theory states that the cell is the basic unit of life; it is the smallest unit that is still considered a living thing. The components of a cell, organelles and molecules, are not living.
According to the biology department of the University of Miami, the key to cell theory is the proposition that all living things are made of cells. Every organism, no matter how complex, is made up of an intricate system of cells. Some organisms are unicellular, comprised of a single cell.
Prior to the universal acceptance of cell theory, a common belief was that of spontaneous generation, the notion that life springs from abiotic factors. The biology department of the University of Miami recognizes German philosopher Lorenz Oken as the first person to articulate this principle in 1805 when he stated "All living things originate from and consist of cells."