PHILOSOPHY AND FUN OF ALGEBRA
most of the people belonging to him. Macbeth was a brilliant and successful soldier; his imagination suggested to him that he had it in him to rise rapidly to fortune and power. He might become Thane of Cawdor, and some day even King of Scotland. His imagination was so vivid that he pictured three old women going through some heathen incantation and predicting to him that he would be Thane of Cawdor and King. Here was a road open, along which it was quite sure that his mind would travel easily if he would let it do so. The question was: Should he let it go along that road? Now there were living at the time a Thane of Cawdor and a King of Scotland. While they lived, he could not be either. The commandments say, "Thou shalt not covet thy neighbour's goods." Here was a danger signal. If Macbeth had known as much as Shakespeare knew about the art of sound thinking, he would immediately have said to himself, "'Cawdor' and 'King' are the roads that I had better not travel along just now, for fear the wheels of my mind should get too much way on, and
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