''I ought to say that I accept Amperes theory as the best present representation of facts, but that still I hold it with little reserve. This reserve is more a general feeling than any thing founded on distinct objections to it. Remember I am no Mathematician. If I were one and could go into a closer examination of the theory than is at present possible for me I might have no doubts left; but all my mathematics consists in that rough natural portion of geometry which every body has more or less. Hence the reason why I have never put my facts into terms of Amperes theory; and why I cling to the relations of Magnetic & Electric forces as the simplest I can perceive; these again are readily distinguished in practise and hence the most convenient if not the best for an experimentalist to refer to. I wish most sincerely some mathematician would think it worth his while to do that for the facts which I can not do for them.''
In a letter of Faraday to William Whewell (19 September 1835), in James (ed.), The Correspondence of Michael Faraday, Vol. 2, 1832-1840, p. 278.