Language Point 10

How they do it is a mystery but they must come from somewhere. (Para. 2)
Meaning: How these ideas came to your mind is a mystery; no one can understand. But they must have come from somewhere, an unknown source.
mystery: something that is not fully understood
Many people have tried to solve the problem but without success; it is a mystery that the girl found the solution to it in just a minute.

许多人设法解决这个问题，但都没有成功; 这个女孩仅在几分钟内就把它解决了，真是件怪事。