Friendship is the capacity of two human beings to be with each other in caring and sharing with honesty."" And that's about as deep as it goes, folks. There are some desperate attempts to tap-dance through categories of friends: ""True-Blue,"" ""Casual Friends,"" and ""Friendly Acquaintances"" are the main levels, with such enlightening subdivisions as ""Dumpers,"" ""Pygmalion Pals,"" and ""Jewish Mothers."" Adelaide Bry, who pigeonholed the varicolored world of therapy in Getting Better (1978), now suggests ""using"" friends as therapists rather than as substitute parents or masters. Should you doubt your own judgment, there are even ways to determine whether a particular friend suits your need; test for a True-Bluer, for example, by spicing your phone conversations with non sequiturs about Humpty Dumpty--the real True-Bluer will be listening. Ready yourself for the rigors of friendship by practicing telling the truth into a tape recorder. And so on. Chattily: ""Friendship is becoming the New Movement."" Fortunately, it will probably survive even non-books like this one.