Purity, or the Attempt to Be More Than Human
In pursuing the impulse for goodness, the ego may identify with an inhuman image of purity. But purity is only applicable to thought--nothing is pure in real life. No actions are pure. Actions can, however, be wholesome if they promote the life process. Motives are rarely pure, because humans have many drives--safety, pleasure, love, altruism, self-interest--that should intermingle. Trying to nail down and cleanse motives is a red herring because it is actions humans are responsible for. (Motives are after all, involuntary in the short and medium run.) Purity is often attempted in diet (food is nurture), niceness, non-aggression, or sexuality.
The search for purity often arises out of early rejection (or conditional acceptance which is the same thing). Trying to be pure tends to inaction, because if nothing is done, nothing is regretted. Except eventually some 'impurity of omission' arises. Neurotic guilt is the belief that one hasn't done enough. This undeserved guilt leads many people to try to 'be pure' but purity is not an attainable target and so guilt actually multiplies.