In the Parasha of this week we see Yitro, a non-Jew, give an advice to Moshe, and Moshe listens to his voice. We conclude that Yitro's words contained a truth that Moshe until then did not have. It is a lesson for the generations: We must accept the truth from whoever says it. This is not simple. It can happen that one "truth" contradicts another "truth", and a struggle ensues, a struggle for the truth. The truth needs to be redeemed. We need to fight for the completion of the Torah. This is the reason for the long Galut, and for the history of Judaism. It is the reason for the long history of mankind. It is the purpose of evolution. It is the purpose of Creation. We need to establish the truth, bit by bit. And we need to say of each bit who said it first.
"Concerning the faith in man it is said in Parshat Nitzavim: "And not with you alone did I establish a covenant, but with those who are here with us and with those who are not here today..." Therefore each and everyone of us, our children and grandchildren until the conclusion of all the generations who have entered the covenant, are duty bound to examine the secrets of the Torah and to straighten out our faith concerning it by accepting the truth from whomever says it..."
(Rav Eliezer Ashkenazi)