And why are there twenty shillings to our sovereign? Again the real reason lies in Babylon. The Greeks learnt from the Babylonians the art of dividing gold and silver for the purpose of trade. It has been proved that the current gold piece of Western Asia was exactly the sixtieth part of a Babylonian _mnâ_, or _mina_. It was nearly equal to our sovereign. The difficult problem of the relative value of gold and silver in a bi-metallic currency had been solved to a certain extent in the ancient Mesopotamian kingdom, the proportion between gold and silver being fixed at 1 to 13-1/3. The silver shekel current in Babylon was heavier than the gold shekel in the proportion of 13-1/3 to 10, and had therefore the value of one tenth of a gold shekel; and the half silver shekel, called by the Greeks a drachma, was worth one twentieth of a gold shekel. The drachma, or half silver shekel, may therefore be looked upon as the most ancient type of our own silver shilling in its relation of one twentieth of our gold sovereign.(10) I shall mention only one more of the most essential tools of our mental life—namely, our _figures_, which we call Arabic, because we received them from the Arabs, but which the Arabs called Indian, because they received them from the Indians—in order to show you how this nineteenth century of ours is under the sway of centuries long past and forgotten; how we are what we are, not by ourselves, but by those who came before us, and how the intellectual ground on which we stand is made up of the detritus of thoughts which were first thought, not on these isles nor in Europe, but on the shores of the Oxus, the Nile, the Euphrates, and the Indus. Now you may well ask, _Quorsum hæc omnia?_ What has all this to do with freedom and with the free development of individuality? Because a man is born the heir of all the ages, can it be said that he is not free to grow and to expand, and to develop all the faculties of his mind? Are those who came before him, and who left him this goodly inheritance, to be called his enemies? Is that chain of tradition which connects him with the past really a galling fetter, and not rather the leading-strings without which he would never learn to walk straight?