Recursion

... loosely speaking means "repetition".  More precisely, it means a repeated 
enfolding-within, such as the play within a play in Hamlet, or the play 
within a play within a play in Rosencrantz and Guildenstern are Dead, 
itself a play derived from Hamlet.

Recursion is a technique used by mathematicians and computer scientists in 
which inward repetition, with simple variation, is used to create images of 
great beauty and complexity, such as the recursive structure of fractals, or 
fractal images of clouds, mountains, ferns and trees.

Recursion is a technique used by nature in which repetition, with simple variation, 
is used to create structures of great beauty and complexity, such as the construction 
of real clouds, real mountains, real ferns and trees from atoms and from the forces 
that bind them.

Recursion is a technique used by people in which repetition, with simple variation, 
is used to create beings of great complexity and beauty, such as the growth of human 
beings from the repeated division of single cells, themselves created by the joining 
of cells that were once themselves divided.