Bronowski[1]:
Physics is not events, but observations; relativity is the understanding of the world, not as events, but as relations.
Smolin (1996: 289-90):
Indeed, for me the most important idea behind the developments of twentieth-century physics and cosmology is that things don’t have intrinsic properties at the fundamental level; all properties are about relations between things. This is the basic idea behind Einstein’s general theory of relativity, but it has a longer history; it goes back to at least to the seventeenth-century philosopher Leibniz, who opposed Newton’s ideas of space and time because Newton took space and time to exist absolutely, while Leibniz wanted to understand them as arising only as aspects of the relations among things. For me, this fight between those who want the world to be made out of absolute entities and those who want it to be made only out of relations is a key theme in the story of the development of modern physics. Moreover, I’m partial. I think Leibniz and the relationalists were right, and that what’s happening now in science can be understood as their triumph.
To model is to systematise categorisations, the valeur of each categorisation being defined by its relations to other categorisations. Individual categories are necessary but not sufficient: the function of each depends on the function of others, just as the function of a neuronal group depends on the functions of other neuronal groups, and the function of a gene depends on the functions of other genes. The process of categorising (analysis) distinguishes individual units, but these are not categorised without reference to what they differ from. Information is difference, in relation to other difference.
Footnote:
[1] The Ascent Of Man episode 7: The Majestic Clockwork.