Ricardo had worked out the main outlines of the 'Classical Political Economy': the system which to his disciples appeared to be as clear, consistent, and demonstrable as Euclid; and which was denounced by their opponents as mechanical, materialistic, fatalistic, and degrading. After triumphing for a season, it has been of late years often treated with contempt, and sometimes banished to the limbo of extinct logomachies. It is condemned as 'abstract.' Of all delusions on the subject, replies a very able and severe critic,[336] there is none greater than the belief that it was 'wholly abstract and unpractical.' Its merits lay in its treatment of certain special questions of the day; while in the purely scientific questions it was hopelessly confused and inconsistent. Undoubtedly, as I have tried to point out, Malthus and Ricardo were reasoning upon the contemporary state of things. The doctrine started from observation of facts; it was too 'abstract' so far as it neglected elements in the concrete realities which were really relevant to the conclusions. One cause of confusion was the necessity of starting from the classification implied in ordinary phrases. It is exemplified by the vague use of such words as 'capital,' 'value,' 'supply and demand.' Definitions, as is often remarked,[337] come at the end of an investigation, though they are placed at the beginning of an exposition. When the primary conceptions to be used were still so shifting and contradictory as is implied in the controversies of the day, it is no wonder that the formulæ should be wanting in scientific precision. Until we have determined what is meant by 'force' we cannot have a complete science of dynamics. The economists imagined that they had reached the goal before they had got rid of ambiguities hidden in the accepted terminology. Meanwhile it will be enough if I try to consider broadly what was the nature of the body of statements which thus claimed to be an elaborated science.