Chocolate contains substances called phenylethylamine and seratonin, both of which (put simply), are mood lifting agents found naturally in the human brain. They are released into the nervous system by the brain when we are happy and when we are experiencing feelings of love, passion or lust. This causes rapid mood change, a rise in blood pressure and increasing heart rate, inducing those feelings of well being, bordering on euphoria usually associated with being in love.
Eating chocolate also releases phenylethylamine and seratonin into the system producing those same euphoric effects, plus it can give a substantial energy boost thus increasing stamina (at the critical moment?) so it's probably these effects which gave rise to chocolates reputation as an aphrodisiac.
The fact that chocolate makes you feel like you are in love was starting to sound pretty good, except that, in my case, after eating two squares of Lindt's 95% pure cocoa, I feel as before eating them with not much difference.
Just like coffee, chocolate contains cafeine but this cafeine does not stimulate me much. I used to drink more black coffee several years ago always without sugar added. Now I can easily drowse while drinking coffee. I guess that might explain why chocolate doesn't have much effect on me.
Would you like to share your experience on this wonderful delight? Go ahead and contribute to this thread.