Jan Mass had nearly reached his hundredth year when this was written, and it is no wonder that Van Helmont, who upon a fantastic analogy had really prescribed an efficient tonic, should have accounted by the virtue of his prescription for the health and vigour, which a strong constitution had retained to that extraordinary age. There is no reason for doubting the truth of his statement; but if Van Helmont relied upon his theory, he must have made further experiments; it is probable therefore that he either distrusted his own hypothesis, or found upon subsequent trials that the result disappointed him. Van Helmont's works were collected and edited by his son Francis Mercurius, who styles himself _Philosophus per Unum in quo Omnia Eremita peregrinans_, and who dedicated the collection as a holocaust to the ineffable Hebrew Name. The Vita Authoris which he prefixed to it relates to his own life, not to his father's, and little can be learnt from it, except that he is the more mystical and least intelligible of the two. The most curious circumstances concerning the father are what he has himself communicated in the treatise entitled his Confession, into which the writer of his life in Aikin's Biography seems not to have looked, nor indeed into any of his works, the articles in that as in our other Biographies, being generally compiled from compilations, so as to present the most superficial information, with the least possible trouble to the writer and the least possible profit to the reader,—skimming for him not the cream of knowledge, but the scum.