Tested by this standard, very few of the ancient writers have obtained such a measure of appreciation as has been accorded to Diodorus. Something like three-fourths of what he wrote has been lost, it is true; but in fairly estimating the import of this, one must consider the bulk of what remains. The briefest comparison supplies us with some very interesting data. It appears that, of the entire series of the predecessors of Diodorus, no single historian has left us anything like a comparable bulk of extant matter. Only one predecessor in any field of literature, namely, Aristotle, greatly exceeds him in this regard, and a single other writer, Plato, about equals him. Turning to the contemporaries of Diodorus and to his successors in the use of the Greek language, a similar result is shown. A single writer exceeds him in output. This is Plutarch, the biographer and philosopher rather than historian proper. No other Greek writer in any field equals Diodorus, though two historians, Dion Cassius and Dionysius of Halicarnassus, are within hailing distance. When one reflects on the actual labour implied by the preservation of any manuscript throughout the long generations of the middle ages, these data speak volumes for the aggregate judgment passed upon the work of Diodorus by posterity. Of the long list of Greek historians,--a list mounting far into the hundreds, as proved by fragmentary remains,--only three as ancient as Diodorus have fared better than he, these three being Herodotus, Thucydides, and Xenophon. But the entire bulk of the works of these three writers does not so very greatly exceed the bulk of the extant writings of Diodorus. The works of Herodotus and Thucydides together do not comprise more matter than is contained in books eleven to twenty of Diodorus, which are preserved _en bloc_.