Being without any fixed occupation, he devoted his leisure to arranging and cleaning the contents of his museum, and writing out a catalogue of them. They consisted of anatomical preparations and insects, of the latter of which there were nearly three thousand distinct species. These were all described and arranged into classes, and the entire structure of many of them had been demonstrated by the most minute dissection. He then published his Treatise on the Ephemeris, which he had commenced when in France, and which is considered as one of the most remarkable productions of any age. He did not, however, venture upon this step without consulting Bourignon. These arrangements completed, he now determined in earnest to lead a holy life, and being desirous of a personal consultation with his directress, he went to Holstein, where he remained with her some time. On returning to Amsterdam, he again endeavoured to dispose of his museum, but without success; and his sister, who had hitherto presided over the domestic establishment, happening at this time to be married, his father resolved upon living with his son-in-law, so that he was obliged to look out for another residence. On this occasion his allowance was limited to 200 florins, and as he could not find any one to purchase his collection he was reduced to great perplexity. However, a thought struck him that he might apply to an old friend, who had formerly treated him with great kindness; but in this he also failed. In the following year, his father died, leaving him heir to his property, which was sufficient for his support; but he became involved in disputes with his sister, which, together with his assiduous endeavours to discharge his religious duties, so agitated his mind, that he was again seized with a severe ague. For three entire months he was confined to his bed, and even when the accessions of the fever had become more gentle and less frequent, he still persisted in remaining in the house. In vain did his friends, Sladus, Ruysch, Schrader, Hotton, and Guenellon, urge upon him the propriety of adopting means for improving his health. He would not yield to their proposals; and, when they still persisted, at length maintained an obstinate silence.