Scientific theory is a contrived foothold in the chaos of living phenomena.

I am now convinced that we have recently become possessed of experimental evidence of the discrete or grained nature of matter, which the atomic hypothesis sought in vain for hundreds and thousands of years. The isolation and counting of gaseous ions, on the one hand, which have crowned with success the long and brilliant researches of J.J. Thomson, and, on the other, agreement of the Brownian movement with the requirements of the kinetic hypothesis, established by many investigators and most conclusively by J. Perrin, justify the most cautious scientist in now speaking of the experimental proof of the atomic nature of matter, The atomic hypothesis is thus raised to the position of a scientifically well-founded theory, and can claim a place in a text-book intended for use as an introduction to the present state of our knowledge of General Chemistry.

This is the essence of mixing. Expressed informally, ‘mixing is if we can get everywhere from anywhere’.

Here is the world, sound as a nut, perfect, not the smallest piece of chaos left, never a stitch nor an end, not a mark of haste, or botching, or second thought; but the theory of the world is a thing of shreds and patches

. . .a scientific theory is just a mathematical model we make to describe our observations: it exists only in our minds. So it is meaningless to ask: which is real, "real" or "imaginary" time? It is simply a matter of which is the more useful description.

Scientific theories are tested every time someone makes an observation or conducts an experiment, so it is misleading to think of science as an edifice, built on foundations. Rather, scientific knowledge is more like a web. The difference couldn’t be more crucial. A tall edifice can collapse – if the foundations upon which it was built turn out to be shaky. But a web can be torn in several parts without causing the collapse of the whole. The damaged threads can be patiently replaced and re-connected with the rest – and the whole web can become stronger, and more intricate.