We start with the conquest of time and distance. That is to say, the kind of knowledge we need to keep track of the seasons and to find our whereabouts in the world we inhabit. One depends upon the other. Making a calendar and navigating a ship depend on the same kind of knowledge, and we shall not be able to keep the two issues apart. Much of the mystery which enshrouds contemporary discussion of Relativity will present no difficulty if the use of the ship's chronometer is grasped firmly at the outset. All measurements of time depend on making measurements in space, and localization in space depends on measurements of time.
We used to think of man as a tool-bearing animal, and to divide the preliterate stage of his existence into an old stone age and a new stone age. We now know that the social achievements of mankind before the beginning of the written record include far more important things than the perfection of axes and arrowheads. Three discoveries into which he blundered many millennia before the dawn of civilization in Egypt, Sumeria, or Turkestan, are specially significant. With the aid of the dogs which followed him and prowled about his camp fires, he began to herd instead of to hunt. He learned to scatter millet and barley, to store grain to consume when there were no fruits to gather. He collected gold nuggets and bits of meteoric iron, and, it may be, noticed the formation of copper from the green pigment that he used for adornment, when it was heated in the embers. The sheep is an animal with seasonal fertility, and cereal crops are largely annual. In domesticating the sheep and learning to sow cereals, man therefore made a fateful step. The recognition of the passage of time now became a primary necessity of social life. In learning to record the passage of time man learned to measure things. He learned to keep account of past events. He made structures on a much vaster scale than any which he employed for purely), domestic use. The arts of writing, architecture, numbering, and in particular geometry, which was the offspring of star lore and shadow reckoning, were all by-products of man's first organized achievement, the construction of the calendar. Shakespeare anticipated Sir Norman Lockyer when he wrote: "Our forefathers had no other books but the score and the tally."
Science began when man started to plan ahead for the seasons, because planning ahead for the seasons demanded an organized body of continuous observations and a permanent record of their recurrence. In an age of wireless transmission, of mechanical clocks and cheap almanacs, we take time for (granted. Before there were any clocks or simpler devices like the hour-glass or the clepsydra for recording the passage of time, mankind had to depend on the direction of the heavenly bodies, sun by day and the stars by night. Already in the hunting and food gathering stage the human race had probably learned to associate changes in vegetation, the mating habits of animals, and the recurrence of drought or floods, with the rising and setting of bright stars and star clusters immediately before sunrise or in evening twilight. When the great agrarian revolution reached its climax in the dawn of city life, a technique of timekeeping emerged as its pivotal achievement. What chiefly remain to record the beginnings of an orderly routine of settled life in cities are the vast structures which bear eloquent witness to the primary social function of the priesthood as custodians of the calendar.
The temple, with its corridor and portal placed to greet the transit of its guardian star or to trap a thin shaft of light from the rising or setting sun of the quarter-days; the obelisk or shadow clock; the Pyramids facing equinoctial sunrise or sunset, the pole and the southings of the bright stars in the zodiac; the great stone circle of Stonehenge with its sight-line pointing to the rising sun of the summer solstice -- all these are first and foremost almanacs in architecture. Nascent science and ceremonial religion had a common focus of social necessity in the observatory-temple of the astronomer-priest. That we still divide the circle into 360 degrees, that we reckon fractions of a degree in minutes and seconds, remind us that men learned to measure angles before they had settled standards of length or area. Angular measurement was the necessary foundation of timekeeping. The social necessity of recording the passage of time forced mankind to map out the heavens. How to map the earth came later as an unforeseen result.
It is a common belief that mathematics is the hallmark of science, and some people are apt to imagine that the introduction of a little mathematics into subjects like economics entitles them to rank as genuine science. The truth is that science rests on the painstaking recognition of uniformities in nature. In no branch of science is this more evident than in astronomy, the oldest of the sciences, and the parent of the mathematical arts. Between the beginnings of city life and the time when human beings first began to sow corn or to herd sheep, ten or twenty thousand years -- perhaps more -- may have been occupied in scanning the night skies and watching the sun's shadow throughout the seasons. Mankind was learning the uniformities which signalize the passage of the seasons, becoming aware of an external order, grasping slowly that it could only be commanded by being obeyed, and not as yet realizing that it could not be bribed. There is no hard and sharp line between the beginnings of science and what we now call magic. Professor Elliot Smith rightly says that magic is the discarded science of yesterday. The first priests were also the first scientists and the first civil servants. As custodians of the calendar, they created an organized body of reliable knowledge from the common experience of herdsman and cultivator.
To understand how a science of astronomy is possible, we have to acquaint ourselves with uniformities of nature, once familiar features of the everyday life of mankind. They are no longer part of the everyday life of people who live in large cities. So, many readers of this book will need to be told what they are. Looking at them retrospectively we can arrange them under four headings.