When a constraint exists advantage can usually be taken of it. — W. Ross Ashby

"Throughout, we shall be exemplifying the thesis of D. M. MacKay: that quantity of information, as measured here, always corresponds to some quantity, i.e. intensity, of selection, either actual or imaginable"

"The concept of "variety" [is] inseparable from that of "information."

"By a state of a system is meant any well-defined condition or property that can be recognised if it occurs again. Every system will naturally have many possible states."

"Every stable system has the property that if displaced from a state of equilibrium and released, the subsequent movement is so matched to the initial displacement that the system is brought back to the state of equilibrium. A variety of disturbances will therefore evoke a variety of matched reactions."

"If intellectual power is to be developed, we must somehow construct amplifiers for intelligence — devices that, supplied with a little intelligence, will emit a lot."

"Every isolated determinate dynamic system, obeying unchanging laws, will ultimately develop some sort of organisms that are adapted to their environments."