数学不是沿着一条清理得很好的高速公路小心行进，而是进入一个陌生的荒野的旅程，探险者常常会迷路。
Mathematics is not a careful march down a well-cleared highway, but a journey into a strange wilderness, where the explorers often get lost.
富贵如住宿旅店，只有谨慎勤劳才可以久居；贫贱如破衣服，只有勤俭才能脱去贫穷的破衣。