The breeding of horses is usually carried on, first, in order to procure directly or indirectly the necessaries of life, and, second, to secure a profit. Occasionally they are bred simply for pleasure or pastime.

It would be out of place to discuss here what amount of surplus or reserve it is best to accumulate, or how fully the so-called necessaries of life should be supplied, in order that man may arrive at his best estate. We enter at once, therefore, upon the discussion of the laws and forces which underlie animal life and reproduction, growth, development and change, with the paramount object of increasing the quality and quantity of the necessaries of life, of diminishing labor, of increasing knowledge, and of adding to the world's surplus and pleasure.

If we attempt to investigate the laws and forces which govern animal growth and reproduction, we are necessarily brought face to face with the sciences and their application to reproduction, life and growth. The ancient authors enumerated seven of them, and Pope adds one more:

"Good sense, which only is the gift of Heaven, And, though not science, fairly worth the seven."

So many mistakes have been made in the application of science to the breeding and improving of domestic animals, particularly horses, and so much success has been attained through careful and timely attention to the details of feeding and surroundings by men untrained in science, that the fact is often forgotten that their successes are due to the practical application of science which they have unwittingly absorbed. This has resulted in belittling science - that is, ascertained truth or knowledge duly arranged, - and in giving the credit to "common sense."

Such rapid advancement has been made within the last thirty years in the breeding and rearing of horses, that he who would now reap the largest reward must not only master the most minute details of breeding, but must also make himself acquainted with the many laws and forces that are ever acting, modifying and limiting each other, - some of them knowable, some of them unknown in our present state of research.

Much valuable information may be gained by studying the effects of laws with which we are only partially acquainted, or of which we are totally ignorant. For instance, we know that exercise or motion under certain conditions produces growth and development; under others the same exercise may produce weakness and decay. If we exceed the limit of exercise too far, we may not only fail to secure development, but may produce lasting injury. Observing results from certain methods, we try to formulate in part, at least, the laws with which we are only imperfectly acquainted. We should not discard or hold any knowledge lightly (because our knowledge is not complete); neither should we discard knowledge which is not absolutely correct. Most knowledge is only relatively correct, but, if it is accurate enough to aid us in our research and enlighten our judgment, it is still valuable. The chemist cannot make his analyses absolutely correct. Are they therefore of no value? The steel rule may be shortened by a little cool air, and lengthened by the mild rays of the sun; is it therefore of no value in measuring length and breadth because it is slightly inaccurate when placed under slightly changed conditions? While the steel rule is never again absolutely a foot long after it is made, except when placed in the same temperature as that in which it was made, yet it varies only within narrow limits. So, although it is seldom absolutely accurate, it serves the world well for all uses to which it is ordinarily put.

We speak of the "science" of breeding. This term is used loosely, and is too often made to cover both the science and the practice of breeding. Science is usually defined as ascertained facts, truths logically arranged. For instance: it is a fact that like produces like under exactly the same conditions. If two parents are similar, or of nearly identical blood, and their environment and potency similar, their offspring will be similar to the parents. But it is also a fact that precisely the same conditions, in all particulars, are never present in the production of any two animals, and, therefore, no two animals, though from the same parents, are exactly alike. Thus it appears that the forces of reproduction and growth, food and environment, tend to produce variation. Slight variations along one or more lines, continued and accelerated from generation to generation, through long periods of time, may produce very marked and permanent changes. If the acquired characteristics, due to variation, have been present for a long time, and the chief conditions which produced the variation are continued, then such acquired qualities are transmitted from parent to offspring, with a good degree of certainty; but perhaps not so surely as are the characteristics which were acquired earlier, when animals lived under less artificial conditions. Happily, the variations either for better or for worse, like those in the steel rule, are usually within very narrow limits in a single generation or even in several generations. If it were not so, one species would merge into another, breeds and families be extinguished, and finally lost in one indistinguishable whole. Variations in stock-breeding, like the errors due to variations in the steel rule, if multiplied, often may produce marked results.

The St. Louis bridge, though accurately drafted and accurately made, would not go together when moved to another and warmer temperature than that in which the pieces which constituted it were shaped. James B. Eads did not lay this trouble to chance or to sport. He knew that the lengthening of the girders of the bridge was due to an inexorable law, and, taking advantage of the law that governs expansion and contraction of iron and steel, he shortened the girders of the bridge by packing them in ice, thereby overcoming the difficulty.

There is no such thing as chance, in the sense in which the word is often used. Laws, or modes of operation, reign supreme in the natural world, ever the same when subject to the same conditions. And this is not all. Every effect produced by the operation of a law is registered in some form, and somewhere. The vibration of the earth's particles produced by the eruption of Mount Pelee, in the Island of Martinique, were recorded in England by a most delicate and ingenious instrument. The particles of earth half way around the globe could not vibrate or hit each other without affecting all other particles of which the earth is composed. As breeders of horses, we are first to discover, if possible, Nature's modes of action and the effects of them. Failing in this, we attempt to decipher what has been registered, in order that something may be learned of the laws which produced the effects.

The American bison (Bos Americanus) illustrates well the power of a species to perpetuate a very close resemblance in the individuals. This is partly due to the similarity of the parents, partly to similarity of food and conditions, and partly to indiscriminate breeding. If variation from any cause appeared in one locality during a single generation, it would not be likely to be perpetuated. The bison roams over a large territory and mixes with other herds, so that the conditions which produced the variation would not be likely to be present again, neither would the parents of the animal in which the variation appeared be likely to breed together again. The variation would, therefore, almost certainly disappear, or, at the most, would make only a feeble and imperceptible impression on the common herd. Constant intermingling of animals which roam over wide areas tends to produce similarity; while, if the area be small, as when animals are reared in enclosed parks, variation is likely to be perpetuated. Wild species, even when kept pure, when brought under domestication often show marked variations from the original type, due not to admixture of blood, but to changed food and environment. Even when slightly restrained, as are the wild cattle of Chillingham Park, variations are quite common. Darwin, in speaking of the variations in the Park cattle, says that animals nearly in a state of nature, and exposed to nearly uniform conditions, if not allowed to roam freely, or to cross with other herds, do not remain as uniform as wild, unrestrained animals.

The feathered tribes usually make the first marked departure from the feral type in the color of the feathers. A good illustration of this is found in the many colored turkeys, all originating from a dark-bronzed wild turkey. Horses, cattle and pigs, when brought under domestication, usually vary first in form, although they may vary in color as well. The myriad departures from reproduction of exact likeness which we may see everywhere and at all times, do not argue that something has occurred without a cause, or that a miracle has been wrought, or that blind chance reigns instead of law. To perpetuate, then, the qualities and characteristics of a species or breed virtually intact, all the conditions must be made similar to those which prevailed in producing the breed. It should not be forgotten that horse-breeders usually aim at something more than simply preserving valuable qualities: they desire to produce variation for the better. This is difficult in ordinary practice with animals already highly improved. Many are satisfied if they can reproduce animals which are as good as the parents. If the standard of excellence were not so high, it would not be difficult, with our present knowledge, to make rapid advancement. I am speaking here of the best specimens of the various breeds of horses.

The differences are usually slight in the offspring of well-bred animals; but, however slight they may be, they are worth noting and studying. Just here is where the beginner fails. He does not lay enough stress on small things; and the eye and judgment, not being well trained, fail to see clearly or to interpret correctly the variations which tend toward improvement or deterioration. Variations, when multiplied through several generations, are easily discovered; but the cause or causes which produce slight variation in the immediate offspring are likely to elude our search unless extended knowledge and wide experience are possessed. Therefore the breeding of full-blooded animals designed for progenitors of their race should be in the hands of experts.

In order to study the breeding of horses critically, the subject is divided into eight principal heads - Inheritance, Food, Climate, Habit, Selection, Relative influence of Sire and Dam, the Governing of Sex, and Atavism.