凡陽必刚，刚必明，明则易知；凡陰必柔，柔必暗，暗则难测。
凡是陽性必刚强，刚强一定光明，光明则容易了解。凡是陰性必柔弱，柔弱一定陰暗，陰暗则难以预测。
The night is a great forest, but the stars are its trees.
Learning is not a passive process; it involves the active construction of knowledge.
经济学家的角色既是科学家，又是工程师。