“At the same time, the very vastness of space acts as a strong discouragement; people complain that they cannot visualize the interstellar or intergalactic scale, and so refuse to investigate the matter further. This is as short-sighted as it is sad. In the first place there is no need to ‘visualize’ the universe in order to gain some idea of its workings—for no astronomer can really comprehend the enormity of his field of study. It is simply a matter of getting used to dealing with very large units of distance. On the Earth we might arbitrarily define 1 foot as a small distance, 1/1,000th of a millimetre as a very small distance. The astronomical equivalents of ‘very small’ and ‘small’ could be 1 mile and 1 light-year (5,880,000,000,000 miles). We can no more imagine 1/1,000th of a millimetre than a million miles—but no one is afraid of looking through a microscope! And at the same time there is no doubt which is the more impressive.”