Tosfos asks why the Gem. doesn't bring a proof that money is a good kinyon to acquire fields from 'S'dei Efron'.
Tosfos answers that since in that case the field was acquired from a 'goy' there is no proof that the same 'kinyon' would work to acquire a field from a fellow 'Yid'.
Yet when the Gem. asks the same question of 'Kesef Minolon' in regards to being 'Mekadesh an Isha' on 2a; the Gem. has no problem with learning it out from 'Sdei Efron'. Why so?! Perhaps, there as well, 'Kesef' only works by a 'Goy'!
Kol Tuv
alex lebovits, toronto, canada
This question is also right on target and the mefarshim ask it:-
(1) The Maharsha here answers that when the Gemara above 2a derives from Ephron's field that Yisrael do Kidushin with money, the limud is from a Gezera Shava that the word "Kicha" used in the verse "Ki Yikach", concerning marriage, in fact refers to money, in the same way that we know that the word Kicha" used in the verse "Kach Mimeni" concerning Ephron, also refers to money.
(2) The Pnei Yehoshua explains this slightly further based on Tosfos 2a u'Ksiv (it seems to me that this is the Tosfos that the Pnei Yehoshua is referring to, not Tosfos 2a DH v'Kesef, as suggested in the new editions of the Pnei Yehoshua ). Tosfos there writes that when the gemara derives from Kach Mimeni that Kicha of kidushin means money, all we are trying to do is to prove that the word kicha implies money in both places, even though there is quite a different implication of what the word kicha means in each case, because kicha for the wife means the husband acquires his wife, whilst kicha for the field means the seller takes the money in return for the field. However, even though the case is quite different, nevertheless what interests us is merely the meaning of the word kicha.
Pnei Yehoshua therefore writes that we do not actually derive from Sdei Ephron that that the kinyan of a wife is through money. If we would have, your question that one cannot derive this from the din of a goy would be a valid one. Instead we merely learn through a giluy milta b'alma - a sort of dictionary definition - that the word kicha means money and then we know automatically that when the Torah says ki yikach, this must mean that the husband is acquiring his wife with money.
KOL TUV
Dovid Bloom