"I hang on to your words because they are to me weighty; and where you say 'I, for my part cannot realise your dissatisfaction with the law of gravitation provided you conceive it according to your own principles' they give me great comfort. I'll have nothing to say against the law of action of gravity. It is against the law which measures its total strength as an inherent force that I venture to oppose my opinion; and I must have expressed myself badly (though I do not find the weak point) or I should not have conveyed any other impression...All I wanted to do was move men (hehe) from the unreserved acceptance of a principle of physical action which might be opposed to a natural truth. The idea that we may possibly have to connect repulsion with the lines of gravitation force (which is going far beyond anything my mind would venture on at present except in private cogitation) shows how far we may have to depart from the view I oppose." - Michael Faraday

Yeah, that's Faraday saying anti-gravity might exist, if he could only unify it with more encompassing lines of force. Note that the "hehe" is my aside. I love the part where he says "your words are weighty". :) The man was funny!