It is a characteristic of all work in physical science that however it may originate in the pure desire for truth, it is very quickly available for practical use, personal comfort, the acquisition of wealth, and national efficiency.  The physicist who calculates the stresses and strains of an aeroplane finds that in teaching man how to control nature he is also providing the means for his struggle, whether in peace or war, in commerce or on the battle-field.  We soon find that the progress of technical skill is curiously inoperative in its effect on human thought and feeling.  Men remain the same whether they ride in a coach, or a train, or a motor-car; it matters little whether they use bows and arrows, or rifles, or hand-grenades, or liquid fire.

Now in education it is the technical side of scientific progress which almost inevitably becomes most prominent, and the greater the advance in knowledge the more will this be true.  The wider the domain of knowledge the greater is the number of those who will be chiefly occupied with the use of the processes and materials that have been discovered and the smaller is the proportion of those who will have reached the border of the known, and will begin the work of exploration into the unknown.  That is, the greater will be the number of those who are the servants and not the masters of science.  A unity of a certain kind we shall have, the unity of those who have learned to pilot an aeroplane, to apply X-rays, to extract the phosphate from iron, or to test cattle for tubercle.  All this may produce a uniformity in the machinery of life, it passes by untouched the motives of action, the beliefs, affections, and interests.  How many illustrations of this do we see around us!  What more glorious illustration of the power of the human intellect can be found than the later developments of electricity, but scarcely had the discoveries been made when we find them seized upon by the man of affairs, and wireless telegraphy becomes the subject of speculation on the Stock Exchange, and a chief instrument of war.  That which the chemist finds in his laboratory is, within a few years, sometimes even a few months, found again in the factory, and perhaps on the field of battle.

Do not let it be supposed that I would underrate the possibility of a deeper unity, but if we would find it we must carry our analysis further back.  The progress of science is in truth not a cause but a result, not an ultimate fact but the symptom of a state of mind.  It springs from that which was brought into Europe consciously at the Renaissance and which we may call the spirit of Greece.  It is that to which we owe not only the investigation and subjection of nature, but equally with it all progress in every department of thought, the analysis of society, whether political or economic, the investigations of the working of human reason, the probing of human passions, and their record in art and literature.