From the 1968 lecture programme:
It was the marvellous imaginary voyages of Lemuel Gulliver which made us see a world of petty six-inch patriots, or of sixty-foot people, large-minded and generous. Dean Swift was not writing science, but he lighted for our minds the meaning of size in our perception and in all human affairs.
In science the scale of things is often decisive. We human beings can view the world from one scale only, our own. But in that world are ants and whales, mountains and seas, planets, stars and atoms. A great deal of their nature is explainable as the consequence of their magntiude, for the fundamental building bricks of all the world, the particles of the physicist, fix a size built somehow into everything material.