In 1905, Albert Einstein provided an explanation for the photoelectric effect, whereby a photon - a "particle", for want of a better term, of light - hitting a surface transfers some of its energy to the surface, sufficient to eject an electron (or, in a similar process, to create an electric current - this is how solar panels work). Similarly, when the warm sunlight comes into contact with my bare skin (especially if it's been a while since I've been out in the sunshine), occasionally it produces an erotic effect, causing me to become sexually aroused.
[description: video depicting non-contact arousal while laying nude in the sunshine]
In a nudist context, this can be somewhat inconvenient, although I have to wonder why this should necessarily be the case. What does it matter if the pleasure you receive from baring your body to the elements is sexual in nature? Presumably, nudists want to prevent nudist situations from "devolving" into licentious orgies. This is understandable. But if we separate "passively receiving erotic stimulation" from "active sexual behavior", then where is the harm in the former? This kind of sexual stimulation is independent of typical acts like intercourse or often even masturbation. For while I might gently caress or apply pressure to my genitals - simply because it feels good - I don't necessarily have the intention of initiating a full-blown masturbatory session.
This flies in the face of the sexist stereotype of the man who demands sex at the slightest provocation of penile stimulation; but that has never been my reality. Perhaps I am atypical, but insofar as there are people like me, who behave the way I do, I don't see what harm that kind of behavior could possibly do, even in the context of an "asexual" nudist environment. Whether the chemicals coursing through your body - the electrical charges, if you will - are the result of athletics, relaxation, massage, the alcohol in your system, your wife scratching your back, or any other "decent" source you can think of, or if they are erotic in nature, I don't see how there is any difference, aside from an unnatural and unhealthy taboo surrounding anything related to sex.
The same logic can be applied to finding nude bodies sexually appealing. As long as you're not some neanderthal that can't help grabbing your crotch every time you see a naked breast, there's no reason why nudists should disavow the very human realization that our bodies are fundamentally sexual in nature. Nudism is not about sterilizing life. It's about having a healthier approach to our bodies. Which means not denying basic truths (and in the process lending evidence to the rest of the world's suspicion that we're nutjobs who simultaneously can't keep our clothes on and yet adamantly refuse to acknowledge that there could be anything sexual about it), but just taking responsibility for our actions and maintaining civility in the face of a more natural, down-to-earth mode of living.
