“Leigh,” said Mr. Thompson, rising from his chair, “sit down here.” Then he pointed to a sheaf of papers on his desk. Tommy sat down. He looked at the sheets on the desk before him and saw rows of figures. But before he could learn what the figures represented Mr. Thompson took a lead-pencil from the tray, gave it to Tommy, and said, “The first number of all, Leigh?” Tommy looked at the top sheet. “Yes,” he said; “it's 8374--” “No. The first of the cardinal numbers!” “One?” “Don't ask me.” “One!” said Tommy, and blushed. “Of course.” Mr. Thompson spoke impatiently. “The beginning, the first step. One! Did you ever study numbers?” “I--” began Tommy, not fully understanding the question. Then, since he did not understand, he said, decidedly, “No, sir!” “Do you know anything of the significance of the number seven?” “In mathematics?” “In everything!” “No, sir.” “Ever hear of Pythagoras?” “The Greek philosopher?” “I see you don't. At all times, in all places, a mystical significance has attached to the number seven. Ask a man to name a number between one and ten, and nearly always he will answer, 'Seven!' Do you know why?” “No, sir. But I am not sure he would answer--” “Try it!” interrupted Mr. Thompson, almost rudely. “It is also a well-known fact that in all religions seven has been the favorite number. Greece had her Seven Sages. There were the Seven Sleepers of Ephesus and Seven Wonders of the Old World. The Bible teems with sevens: the Seven-branched Candlestick, the Seven Seals, the Seven Stars, the Seven Lamps, and so forth. “Abraham sacrificed seven ewes; the span of life is seventy years, and the first artificial division of time was the week--seven days. And the Master multiplied seven loaves and fed the multitude, and there were left seven baskets. And He told us to forgive our enemy seven times, aye and until seventy times seven. And there are seven notes in music and seven colors in the spectrum. Also the superstition about the seventh son of a seventh son is found among all peoples.” “I see!” said Tommy, and wondered. Mr. Thompson looked at Tommy searchingly. Tommy's mind was working away--and getting nowhere! Mr. Thompson now spoke sharply: “Take your pencil and strike out in those sheets every odd number that comes after a one or a seven. Get that?” “Yes, sir.” “Don't skip a single one. I've spent a lot of time explaining. Now rush. Ready?” “Yes, sir,” said Tommy. “Go!” shouted Mr. Thompson, loudly, and looked at his stop-watch.