The Gemara asks whether שטר אירוסין needs to be לשמה - written specifically for the sake of the woman. The Gemara says that just like כסף doesn't have to be minted לשמה so too the שטר קידושין doesn't have to be לשמה.
Now the Ra"n discusses whether one can perform Kiddushin במחובר לקרקע. Geirushin CANNOT be done with מחובר לקרקע, so maybe we learn הויה ליציאה [marriage from divorce] and disqualify Kiddushin במחובר לקרקע. He proves that כסף קידושין is not derived from גירושין [with the היקש of הויה ליציאה] from this Gemara. The Gemara says that just as the coin need not be minted for her sake, so too the שטר קידושין need not be written for her sake. It emerges that כסף קידושין is NOT derived from גירושין. So we can extract from this that despite the fact the גירושין is פסול if מחובר לקרקע, Kesef Kiddushin is valid במחובר לקרקע.
The Ra"n rejects this proof and says that really maybe Kiddushin במחובר לקרקע is פסול as derived from גירושין. The reason that כסף קידושין doesn't require לשמה as does גירושין is b/c it is IMPOSSIBLE for כסף קידושין to be לשמה. The reason is that the woman is not married with the mintage of the coin but with the value [שוויות] of the coin. So minting the coin לשמה would be irrelevant. But when it comes to מחובר לקרקע, we WOULD derive קידושין from גירושין and disqualify it.
But this presents a quagmire: How do we now understand the Gemara??!!! The Gemara says that just like כסף doesn't have to be minted לשמה, so too the שטר קידושין doesn't have to be written לשמה. What is the צושטעל ["comparison" in Swahili]??!! There is no reality that כסף קידושין be לשמה while שטר קידושין CAN be לשמה. So how can we compare the latter to the former??!!
