“The world is but an assembly of present, past, and possible sensations; the affair of science is to analyze and co-ordinate them by separating their accidental from their constant relations.”

Source: Fiction Sets You Free: Literature, Liberty and Western Culture (2007), p. 18.

Source: The Mind and the Brain, 1907, p. 60; Definition of sensation

The Notebooks of Leonardo Da Vinci (1938), I Philosophy
Variant: Science is the observation of things possible, whether present or past; prescience is the knowledge of things which may come to pass, though but slowly.

The Structure of the Universe: An Introduction to Cosmology (1949)
Context: The philosophical consequences of the General Theory of Relativity are perhaps more striking than the experimental tests. As Bishop Barnes has reminded us, "The astonishing thing about Einstein's equations is that they appear to have come out of nothing." We have assumed that the laws of nature must be capable of expression in a form which is invariant for all possible transformations of the space-time co-ordinates and also that the geometry of space-time is Riemannian. From this exiguous basis, formulae of gravitation more accurate than those of Newton have been derived. As Barnes points out...

1960s, Operating Manual for Spaceship Earth (1963)

Source: "Notes on the Theory of Organization," 1937, p. 38

Source: World views. From Fragmentation to Integration (1994), p. 8

Source: Reality; The Search for Objectivity or the Quest for a Compelling Argument (1988), p. 48 as cited in: Vincent Kenny (1989) " Life, the Multiverse and Everything; an Introduction to the Ideas of. Humberto Maturana http://www.oikos.org/vinclife.htm".

Source: Ways of Seeing