In March, Sixteen Hundred Sixty-eight, he was given the degree of Master of Arts. His studies now were of a very varied kind. He was required to give one lecture a week on any subject of his own choosing. Needless to say his themes were all mathematical or scientific. Just what they were can best be inferred by consulting his cashbook, since the lectures themselves were not written out and all memoranda concerning them have disappeared. This account-book shows that his expenditures were for a Gunter's Book (he who invented the Gunter's Chain), a magnet and a compass, glue, bulbs, putty, antimony, vinegar, white lead, salts of tartar, and lenses. And in addition there are a few interesting items such as one sees in the Diary of George Washington: "Lost at cards, five shillings." "Treating at tavern, ten shillings." "Binding my Bible, three shillings." "Spent on my cousin, one pound, two." "Expenses for wetting my degree, sixteen shillings." The last item shows that times have changed but little: this scientist and philosopher par excellence had to moisten his diploma at the tavern for the benefit of good fellows who little guessed with whom they drank. He also had "poor relations" come to visit him; and it is significant that while there are various items showing where he lost money at cards, there are no references to any money won at the same business, from which we infer that while there was no one at Cambridge who could follow him in his studies, there yet were those who could deal themselves better hands when it came to the pasteboards. Evidently he got discouraged at playing cards, for after the year Sixteen Hundred Sixty-eight, there are no more items of "treating at the tavern" or "lost at cards." The boys had tried to educate him, but had not succeeded. In card exploitations he fell a victim of arrested development. I suppose it will not cause any one a shock to be told that "the greatest thinker of all time" was not exactly a perfect man. So let the truth be known that throughout his life Newton had a well-defined strain of superstitious belief running through his character. He never quite relinquished the idea of transmutation of metals, and at times astrology was quite as interesting to him as astronomy. In writing to a friend who was about to pay a long visit to the mines of Hungary, he says, "Examine most carefully and ascertain just how and under what conditions Nature transforms iron into copper and copper into silver and gold." In his laboratory he had specimens of iron ore that contained copper, and also samples of copper ore that contained gold, and from this he argued that these metals were transmutable, and really in the act of transmutation when the process was interfered with by the miner's pick. He had transformed a liquid into a mass of solid crystals instantly, and all of the changes possible in light, which he had discovered, had enlarged his faith to a point where he declared, "Nothing is impossible."