Musar על שמות 3:1

Yitro's words "עתה ידעתי" "now I know," (Exodus 18,11) reflect this new-found knowledge of Yitro (Cain). Cain had murdered because he did not believe that G–d is a judge, that there is justice in the world, and that there is life after death. The Targum Yonathan says that the word "עתה" represents Yitro's new found insight, and that this is the reason that this portion about the installing of a broadly based system of judges was added at Exodus 18,21. (I have not been able to find this in the Targum Yonathan. Ed) The reason Yitro had entrusted (given) his flock to Moses (Exodus 3,1) was that it was symbolic of the sheep he had stolen from his brother Abel in his previous incarnation, the latter having been a shepherd (Genesis 4,2). Moses had not wanted to accept this flock, believing it to be rightfully Yitro's. The Rabbis do not like someone tending the property of an idol worshipper, since the chances are that such property may have been acquired as payment for services rendered to idols. The Torah therefore stresses צאן יתרו, that the flock was not derived from such sources.