The Greeks had no hand in the invention of cannon. One of their historians of the fifteenth century, when speculating on the subject in his narrative for the year 1389, says the Germans were commonly believed to have been the inventors.[121] Could the Greeks, then, have been in possession of saltpetre-mixtures many centuries before? Is it credible that people with intellect as keen as the Greeks employed an explosive for long ages without hitting upon the idea of metal guns? Yet judging from the manner in which Chalcocondyles speaks of cannon in his narrative for 1446, they were even then but little known to the Greeks. “Cannon,” he tells his countrymen, “are formidable instruments, which no armour can resist, and which penetrates through everything.”[122] No historian of the ability of Chalcocondyles would have spoken in this manner about an arm which was well known. The fact that the first recorded use of fire-arrows on Greek soil was made by Persian archers,[123] lends some probability to the view that Greek fire was originally borrowed from the East; but the Greeks assuredly invented the sea-fire which was the palladium of the Empire for several centuries. To the discovery of saltpetre they have no legitimate claim. The claim put forward in their name is based partly on a metaphor,[124] partly on the assumption that the effects of sea-fire could have been only produced by a mixture containing saltpetre; and it cannot be sustained. The hypothesis that Kallinikos compounded a saltpetre mixture ignores the highly probable conclusion that saltpetre was not discovered until the thirteenth century;[125] fails to explain some statements, and is irreconcilable with other statements made by the ancients; and involves many incredible consequences. It may be objected that this conclusion has been arrived at without taking the evidence of the chief witness for the Greeks, Marcus Græcus. Let us examine his _Liber Ignium_. CHAPTER IV MARCUS GRÆCUS (_Du Theil’s text_[126] _with Berthelot’s numeration_) Incipit Liber Ignium a Marco Græco descriptus, cuius virtus et efficacia ad comburendos hostes tam in mari quam in terra plurimum efficax reperitur; quorum primus hic est.