"A constant chattering mind does not allow any happiness, any possibility of happiness, because only a silent mind can look within, only a silent mind can hear the silence, the happiness, that is always bubbling there. But it is so subtle that with the noise of the mind you cannot hear it.
Only in sex the noise sometimes stops. I say "sometimes". If you have become habitual in sex also, as husbands and wives become, then it never stops. The whole act becomes automatic and the mind goes on its own. Then sex also is a boredom." Yoga: The Science of the Soul, Vol 1, Ch 9