You can read commencement addresses from the 19th and early 20th centuries in which the speakers would talk about the beast within and the need for iron character to subdue it.

读一读从19世纪到20世纪初期的学生毕业讲演辞，你就会发现，演讲人都提到了潜藏的兽性和征服它所需要的钢铁般的意志。