During the inauguration of the kohanim, or priests, Aaron and his sons were commanded to sacrifice a ram and place its blood on their ear, thumb, and toe (Exodus 29:20). What is the meaning of this unusual ritual?
Jewish tradition explains that the ear symbolizes everything that we have heard in the past. The thumb represents everything we are doing in the present. The toe represents where we are going in the future. As the priests prepared themselves for service, they had to remember three things: the past, present, and future. Only in that context would they be able to fully serve God.
This was true of the kohanim then, and it is just as true when we serve God today. In order to serve God fully we must be deeply connected to our past, cognizant of the future, and most importantly, rooted in the present. Only through that lens can our service be complete.