Bernini was the first sculptor to realise the dramatic potential of light in sculpture. This is fully realised in his famous masterpiece Ecstasy of Saint Teresa (1645-1652, Santa Maria della Vittoria, Rome), in which the sun's rays, coming from an unseen source, illuminate the saint and the smiling angel about to pierce her heart with a golden arrow.
I would argue that the expression of sublime ecstasy on Saint Therese’s beautiful face, has little to do with her heart. It has everything to do with a swooning orgasm induced by the smiling angel’s golden arrow. The images of her smile and the golden arrow, are simply metaphors for what is really going on.