The alchemists understand well this universal potency of water. In the works of Paracelsus, Van Helmont, Philalethes, Pantatem, Tachenius, and even Boyle, “the great characteristic of the alkahest,” “to dissolve and change all sublunary bodies—_water alone excepted_,” is explicitly stated. And is it possible to believe that Van Helmont, whose private character was unimpeachable, and whose great learning was universally recognized, should most solemnly declare himself possessed of the secret, were it but a vain boast![324] In a recent address at Nashville, Tennessee, Professor Huxley laid down a certain rule with respect to the validity of human testimony as a basis of history and science, which we are quite ready to apply to the present case. “It is impossible,” he says, “that one’s practical life should not be more or less influenced by the views which we may hold as to what has been the past history of things. One of them is _human testimony_ in its various shapes—all testimony of eye-witnesses, traditional testimony from the lips of _those who have been eye-witnesses_, and the testimony of those who have put their impressions into writing and into print.... If you read Cæsar’s _Commentaries_, wherever he gives an account of his battles with the Gauls, you place a certain amount of confidence in his statements. You take his testimony upon this. _You feel that Cæsar would not have made these statements unless he had believed them to be true._” Now, we cannot in logic permit Mr. Huxley’s philosophical rule to be applied in a one-sided manner to Cæsar. Either that personage was naturally truthful or a natural liar; and since Mr. Huxley has settled that point to his own satisfaction as regards the facts of military history in his favor, we insist that Cæsar is also a competent witness {194} as to augurs, diviners, and psychological facts. So with Herodotus, and all other ancient authorities, unless they were by nature men of truth, they should not be believed even about civil or military affairs. _Falsus in uno, falsus in omnibus._ And equally, if they are credible as to physical things, they must be regarded as equally so as to spiritual things; for as Professor Huxley tells us, human nature was of old just as it is now. Men of intellect and conscience did not lie for the pleasure of bewildering or disgusting posterity.