A much abused writer of the nineteenth century said: up to the present philosophers have only interpreted the world, it is also necessary to change it. No statement more fittingly distinguishes the standpoint of humanistic philosophy from the scientific outlook. Science is organized workmanship. Its history is co-extensive with that of civilized living. It emerges so soon as the secret lore of the craftsman overflows the dam of oral tradition, demanding a permanent record of its own. It expands as the record becomes accessible to a widening personnel, gathering into itself and coordinating the fruits of new crafts. It languishes when the social incentive to new productive accomplishment is lacking, and when its custodians lose the will to share it with others. Its history, which is the history of the constructive achievements of mankind, is also the history of the democratization of positive knowledge. This book is written to tell the story of its growth as a record of human achievement, a story of the satisfaction of the common needs of mankind, disclosing as it unfolds new horizons of human wellbeing which lie before us, if we plan our new resources intelligently.
Whether we choose to call it pure or applied, the story of science is not something apart from the common life of mankind. What we call pure science only thrives when the contemporary social structure is capable of making full use of its teaching, furnishing it with new problems for solution and equipping it with new instruments for solving them. Without printing there would have been little demand for spectacles; without spectacles neither telescope nor microscope; without these the finite velocity of light, the annual parallax of the stars and the microorganisms of fermentation processes and disease would never have been known to science. Without the pendulum clock and the projectile there would have been no dynamics nor theory of sound. Without the dynamics of the pendulum and projectile, no Principia. Without deep-shaft mining in the sixteenth century, when abundant slave labour was no longer to hand, there would have been no social urge to study air pressure, ventilation, and explosion. Balloons would not have been invented, chemistry would have barely surpassed the level reached in the third millennium B.C., and the conditions for discovering the electric current would have been lacking.
For this reason the chapters which follow will not adopt the customary division of science into separate disciplines, such as chemistry or biology. The topics dealt with will be grouped under six main themes; the story of man's conquest of time reckoning and earth measurement, of material substitutes, of new power resources, of disease, of hunger, and of behaviour. When the language of mathematics is used, no advanced knowledge will be assumed, and it will present no difficulties if the reader is prepared to do a little work on the examples given. If difficulties arise the reader should not be too easily discouraged, or give up hope. If one chapter or page is difficult to follow, as likely as not the next will be especially easy. The most difficult ones come at the beginning.
If the execution of the task is novel, there is no originality in the conception. The reader who is tempted to think so should reflect on the words with which the great German chemist Liebig addressed the Royal Academy of Sciences at Munich in 1866. Speaking of the Development of Ideas in Physical Science, Liebig said:
The history of physical science teaches us that our knowledge of things and of natural phenomena has, for its starting point, the material and intellectual wants of man and is conditioned by both. . . . Man is not born acquainted with sensible objects and their properties and effects; these notions must be gained by experience. . . . All these conceptions have sprung or have been derived from sensible marks. . . . Since natural phenomena are interconnected like knots in a net, the investigation of particular phenomena evinces that they have in common certain conditions, which as remarked are active things. . . . Having the facts it is our subsequent business to establish their connexion. The facts themselves are obtained through sensual perceptions; when these are imperfect, so will be the knowledge reared on them. We can have no general theoretical propositions except by means of induction, and inductions can be framed only through sensual perceptions. . . . Manifestly therefore the truth of explanations does not depend on the principles of logic alone. . . . The first explanations can, manifestly, be neither definite nor limited, and they must change just in proportion as the facts are more distinctly ascertained and as the unknown ones belonging to the conception are discovered and incorporated in it. The earlier explanations are therefore only relatively false and the latter only therein truer that the contents of the conceptions of things are more comprehensive, determinate and distinct. . . . The conception of time which belongs to the composite notion of velocity was first developed fifteen hundred years after Aristotle. For short intervals the Greeks had not clocks or time measures. . . . Charlemagne's endeavours by the establishment of schools to elevate the intelligence of the rude and ignorant priesthood of the age could have no result, the soil on which culture thrives being not yet prepared. The development of culture, i.e. the extending of man's spiritual domain, depends on the growth of the inventions which condition the progress of civilization, for through these new facts are obtained. . . . Only the free man, not the slave, has a disposition and interest to improve implements or to invent them; accordingly, in the devising of a complicated machine, the workmen employed upon it are generally co-inventors. . . . Greek civilization travelled through the Roman Empire and the Arabians into every European country. . . . The members of the newly originated intellectual class were at first occupied in gaining possession of the treasures of ancient learning. . . . The position and employment of the learned of those times concurred in withdrawing them from contact with the productive classes. Accordingly the literature of that age gives no indication of the degree of the popular civilization and culture; for the knowledge circulating through the masses and absorbed into their thinking, a knowledge originating in their improved acquaintance with physical laws, was not yet stored up in books and was wholly foreign to the learned. . . . With the extinction of the slavery of the ancient world and the union of all the conditions for the evolution of the human mind, progress of civilization and culture is thenceforth assured, indestructible, imperishable. Most of the facts from which the investigator elaborated empirical ideas he had long since received from the metallurgists, the engineers, the apothecaries, and had resolved their inventions into conceptions which the producing classes received back . . . the craftsman, technician, agriculturalist, physician, as in Greece, ask counsel of the theorist. . . . The history of nations informs us of the fruitless efforts of political and theological powers to perpetuate slavery, corporeal and intellectual. Future history will describe the victories of freedom which men achieved through investigation of the ground of things and of truth, victories won with bloodless weapons and in a struggle wherein morals and religion participated only as feeble allies. . . .