Complex sentence: The concept of a "universal constructor" is non-trivial because of the existence of garden of eden patterns but a simple definition is that a universal constructor is able to construct any finite pattern of non-excited (quiescent) cells.
Split into simpler sentences: The concept of a "universal constructor" is non-trivial because of the existence of garden of eden patterns. But a simple definition is that a universal constructor is able to construct any finite pattern of non-excited (quiescent) cells.