Rigor in proof is what separates mathematics from all other sciences.
证明的严谨性将数学与所有其他科学区分开来。
The ordinary is extraordinary if you look closely enough.
The greatest happiness of a teacher is to send groups of children to the other shore of their ideals.
每一本书都是一扇通往未知世界的门，一次探索未知的邀请。