牛痘可以保护人体免受天花的感染。

行为恭敬，待人宽厚，处事平和，心意正直，学圣贤之道，选择良友以求有益身心，改进缺点以求完满。

Every aspect of learning or any other feature of intelligence can in principle be so precisely described that a machine can be made to simulate it.

质量从来不是偶然的；它始终是智慧努力的结果。