Phil was the owner of a herd of twenty highly bred dairy cows. He was a prosperous farmer, but his health was very poor. On the advice of his doctor, Phil decided to winter in Arizona. Before he left, he made an agreement with Freya under which Freya was to keep the cows on Freya's farm through the winter, be paid the sum of $800 by Phil, and return to Phil the twenty cows at the close of the winter.
For reasons that Freya thought made good farming sense, Freya sold six of the cows and replaced them with six other cows. After winter was over, Phil returned from Arizona. Is Freya liable for conversion of the original six cows? Why?