Distrust even Mathematics; albeit so sublime and highly perfected, we have here a machine of such delicacy it can only work in vacuo, and one grain of sand in the wheels is enough to put everything out of gear. One shudders to think to what disaster such a grain of sand may bring a Mathematical brain. Remember Pascal.

I think I have been much of my life an irritant. But some people say that something good came out of my research, something valuable that could be regarded as a pearl, and I can assure those who worked with me it was you who made the pearls and I was merely the grain of sand, the irritant to produce the pearls.
[Recalling how, when increasingly in demand to serve on committees, upon attempting to resign from one, he was told by the chairman 'We want you as an irritant.']

On the basis of the results recorded in this review, it can be claimed that the average sand grain has taken many hundreds of millions of years to lose 10 per cent. of its weight by abrasion and become subangular. It is a platitude to point to the slowness of geological processes. But much depends on the way things are put. For it can also be said that a sand grain travelling on the bottom of a river loses 10 million molecules each time it rolls over on its side and that representation impresses us with the high rate of this loss. The properties of quartz have led to the concentration of its grains on the continents, where they could now form a layer averaging several hundred metres thick. But to my mind the most astounding numerical estimate that follows from the present evaluations, is that during each and every second of the incredibly long geological past the number of quartz grains on earth has increased by 1,000 million.

One summer day, while I was walking along the country road on the farm where I was born, a section of the stone wall opposite me, and not more than three or four yards distant, suddenly fell down. Amid the general stillness and immobility about me the effect was quite startling. ... It was the sudden summing up of half a century or more of atomic changes in the material of the wall. A grain or two of sand yielded to the pressure of long years, and gravity did the rest.

The existing premises, wholly altered by geologic science, are no longer those of Hume. The foot-print in the sand—to refer to his happy illustration—does now stand alone. Instead of one, we see many footprints, each in turn in advance of the print behind it, and on a higher level.

The faculty for remembering is not diminished in proportion to what one has learnt, just as little as the number of moulds in which you cast sand lessens its capacity for being cast in new moulds.

To see a World in a grain of Sand,
And a Heaven in a Wild Flower,
Hold Infinity in the palm of your hand,
And Eternity in an hour.

Who then can calculate the path of the molecule? how do we know that the creations of worlds are not determined by the fall of grains of sand?