SUBLIMATION: The redirection of sexual desire to "higher" aims. Freud saw sublimation as a protection against illness, since it allowed the subject to respond to sexual frustration (lack of gratification of the sexual impulse) by taking a new aim that, though still "genetically" (Introductory Lectures 16.345) related to the sexual impulse, is no longer properly sexual but social. In this way, civilization has been able to estimate "social aims above sexual (ultimately selfish) aims" (Introductory Lectures 16.345). This is not to say that the "free mobility of the libido" (Introductory Lectures 16.346) is ever fully contained: "sublimation is never able to deal with more than a certain fraction of libido"(Introductory Lectures 16.346).