Appraising Grazing Damage in a Field by the Measure of Sixty

"And it grazed in another's field" (Exodus 22:4) - if it went down in its usual manner and caused damage, one pays what it damaged. How so? They appraise a seah's measure of land in that field: how much was it worth before and how much is it worth now. Rabbi says: if it ate fully ripened produce, he pays fully ripened produce; if a seah, a seah; if two seahs, two seahs. From where are these matters derived? The verse says "and it grazed in another's field," teaching that they appraise it in relation to another field. But this verse is needed for "in another's field" - to exclude the public domain! If so, let Scripture write "in his fellow's field," or "in a field belonging to another." What is "another's field"? It teaches that they appraise in relation to another field. Say the whole verse comes only for this; from where do we exclude the public domain? If so, let it write regarding payment "the best of his field and the best of his vineyard he shall pay in another's field." Why does Scripture write it by "and it grazed"? Learn from it two things. How do we appraise? Rabbi Yose bar Chanina said: a seah within sixty seahs. Hizkiyah said: a stalk within sixty stalks. Rabbi Yannai said: a measure within sixty measures. And we do not appraise a single kav by itself, because that improves the position of the one damaged, nor a kav within a field of a kor, because that lowers the position of the one damaged, but within sixty.