What has been the effect of this altered situation upon the writer of history at the present time? On such an extensive field of operations, which has to be cultivated so intensely, he finds himself compelled to contract the scope of his operations; he can only take up very narrow ground. So in many instances he limits himself to a period, or even to a single reign, to a particular class of historical personage, or to some special department of human activity. He looks about for a plot that he can work thoroughly; he concentrates his attention upon some line or aspect of a subject in which he may hope that he has not been anticipated by others. Lord Acton has laid down that 'every student ought to know that mastery is acquired by acknowledged limitation'--he must peg out his small holding and keep within its bounds. Histories are now written by many and various hands--as in the case of the Cambridge Modern History, which already counts numerous volumes--and so the general area is divided and subdivided among experts, each of whom dips deeply into his particular allotment, and takes heavy crops off his ground. Yet the productiveness of the field at large seems still inexhaustible, for there is always some new theory to be established, some fresh vein of facts to be opened, some corrections or additions to be made. Moreover, the experts, while they toil at their own special work, while they attack a difficult problem from different sides, must nevertheless co-operate with each other. Sir William Ramsay, a noted archaeologist, tells us that for a new study of history there is needed a group of scholars working in unison; that the solitary historian is doomed to failure. He adds that the history of the Roman empire has still to be re-written. The late Lord Acton, when as Professor of Modern History at Cambridge he drew out his plan for a modern history that would satisfy the scientific demand for completeness and exactitude, proposed to distribute the work among more than a hundred writers. He observed that the entire bulk of new matter which the last forty years have supplied amounts to many thousand volumes. When history becomes the product of many hands and various minds the artistic element is likely to disappear.