Marx expressed,

 Assume man as man, and his relation to the world as a human one, and you can exchange love only for love, confidence for ocnfidence, etc. If you wish to enjoy art, you must be and artistically trained person; if you wish to have influence on other people, you must be a person who has a really stimulating and furthering influence on other people. Every one of your relationship to man and to nature must be a definite expression of your real, individual life corresponding to the object of your will. If you love without calling forth love, that is, if your love as such does not produce love, if by means of an expression of life as loving person you do not make of yourself a loved person, then your love is impotent, a misfortune.

Art of loving,  25p