Arachin, Chapter 3, Mishnah 4. Our chapter has been collecting cases in which a fixed halachic sum carries within it both a leniency and a stringency, and this mishnah returns to one of the cases already listed back in Mishnah 1: the fine paid by the oness, the violator, and by the mefateh, the seducer. Here the Mishnah explains exactly where the leniency lies and where the stringency lies.
First, the background. The Torah speaks of a man who has relations with a na'arah, an unmarried virgin girl in the stage of life between the ages of twelve and twelve and a half. If he forced her against her will, he pays a fine of fifty sela'im. If he seduced her, meaning that she consented, he either marries her or pays that same fine of fifty sela'im. And in both cases, the violator and the seducer, there are two further payments beyond the fine: compensation for the shame he caused her, and compensation for the loss in her value.
The Mishnah's statement
"Be'oness uvemefateh lehakel ulehachmir": in the case of the violator and the case of the seducer there is a side of leniency and a side of stringency. "Keitzad": in what way?
"Echad she'anas ufitah hagedolah shebakehunah, ve'et haketanah sheb'Yisrael, noten chamishim sela." The offender pays fifty sela in every case alike, whether his victim was a girl born to the loftiest of the kohanic families or a girl from the most obscure family of ordinary Yisraelim, and whether the act was one of force or one of seduction. Her pedigree and her social position have no effect on this payment, because the Torah itself set the figure and fixed it in place.
"Vehaboshet vehapegam, hakol lefi hamevayesh vehamitbayesh." The payments for shame and for devaluation, by contrast, are not fixed at all. They are assessed entirely according to the one who caused the shame and the one who suffered it.
How boshet is assessed
Shame is a relative thing. If the offender is a man of high social standing, the humiliation she suffers is felt as less severe than if he were a person of the lowest sort. And if the girl herself is of high standing, her humiliation is far greater than that of a girl whose standing is lower. Beit Din therefore evaluates the case in practical terms: how much would this girl's father have been willing to pay in order to prevent an embarrassment of this kind from ever touching his household? That sum is what the offender must hand over.
How pegam is assessed
The payment for pegam, her devaluation, is measured by how far her market value as a maidservant has fallen as a result of what was done to her. Beit Din imagines a man who wishes to purchase this young woman as a maidservant for his wife. A virgin commands a higher price than one who is not. The gap between those two prices is the amount of her devaluation, and that is what the offender pays.
Where the leniency and the stringency lie
Now the Mishnah's point comes into focus. Set the flexible payments of shame and devaluation beside the rigid fifty sela of the fine, and you see that the fixed rate can work either way, depending on the girl.
The fifty sela is a leniency when the na'arah comes from a distinguished family. Were the payment assessed according to her standing, the offender would owe a far heavier penalty; but because the Torah set a fixed figure, he discharges his obligation with fifty sela and no more.
And the fifty sela is a stringency when the na'arah comes from an undistinguished family. There an assessment according to her standing would have yielded considerably less than fifty sela, yet he pays the full fixed amount all the same.