Yet this custom is also one of the most mysterious.
Many people also have a custom of shaking out their pockets, or of shaking their tzitzit.
And it was actually Satan, who made himself into a river in order to prevent Avraham from performing the Akeida. The Maharil emphasizes that tashlikh is a commemoration of the Akeida. By going to the river, we demonstrate to God that we recall Avraham's determination to fulfill His command. Not only was Avraham willing to sacrifice his only son, but he was willing to endure great hardship in order to do so. We imply that we too are willing to overcome obstacles to carry out God's will.