It is a slippery slope trying to define what is "natural" when it comes to human desires. For example, is monogamy natural? Is it unnatural to have sexual desires towards minors? Is homosexuality unnatural? Point here is not about what is natural and unnatural, a topic which you can sit here and debate for days. Point here is between mundane sensual pleasures and super mundane happiness. In order to achieve the latter, moderation of the former is advised.