The power of linearity is F=k1+k2 if I come across f of x, y, z equals k1 plus k2, if it is a linear equation, I don't have to go and solve it all over again.

线性的威力是,一个方程，如果它是个线性方程，那么我就不用再去解他了。

麻省理工公开课 - 固态化学导论课程节选