My feeling about technique in art is that it has about the same value as technique in love-making. That is to say, on the one hand, heartfelt ineptitude has its appeal and, on the other hand, so does heartless skill; but what you want is passionate virtuosity.

John Barth (b. 1930) American writer

“An Interview with John Barth,” by Alan Prince and Ian Carruthers, Prism (Spring 1968)
    (Source)

The quotation from the interview (originally credited only to Prince) was also included in the inside dust cover of Barth's short story collection, Lost in the Funhouse (1968), and is sometimes cited to that book.

The longer quote was paraphrased to the form in the graphic above on the dust cover of Charles B. Harris, Passionate Virtuosity: The Fiction of John Barth (1983):

In art as in lovemaking, heartfelt ineptitude has its appeal and so does heartless skill, but what you want is passionate virtuosity.

Harris later gives the full quotation inside his book.

Also used by Barth in "Dunyazadiad," Esquire (1972-07-01), reprinted in Chimera (1972):

Heartfelt ineptitude has its appeal, Dunyazade; so does heartless skill. But what you want is passionate virtuosity.