Being able to take different branches depending on the results of some test is what makes computer programs useful. Good programming style in general demands that you make your intentions explicit in your code. Also, you can have more than one action in each cond clause. Sometimes, this sort of stuff filters into everyday language use. I guess you had to be there.
Equality predicates There are several equality predicates worth knowing about.
These tests take any two LISP objects as arguments, and check to see if they are equal. Naturally, two objects must be of the same type to be equal. You might wonder why four tests are necessary. The reason is that there are degrees of equality. Most of the time you want to know whether two objects look the same, but sometimes you have to know whether they are actually the same object in memory.