Rashi tells us that Reuel is Jethro (Numbers 10:29). He wants to go home and Moses pleads with him to stay with the Jews. One of his arguments to Jethro is: You have been our eyes (Numbers 10:31). A simple way to understand this is that Jethro’s eyewitness account might be more easily believed by Gentiles – he once was one himself – and – and this is not to be sniffed – also more easily believed by skeptic Jews. Seeing is believing. But let me suggest a second way to understand this.
To live a Jewish life, it’s not enough to study the holy books. We were given eyes, ears, noses and other senses and have developed instruments to help us even detect more, like invisible light and weight. We need to look at the world, at nature and even human nature (psychology) to get a full picture of our situation and of how we can be useful.
An important part of observations has been done by professionals, often called scientists. We need to take their findings into account. Sure, classical Christianity has been fighting a war of centuries against science, but that’s because it is focused on thought, feeling, intention and the Beyond and is wary of down-to-earth reality. Not for nothing that religion is called Faith.
But Judaism is rooted in the material world. It is not disembodied. It has no issue with reality or truth. (It is assimilation that makes Jews have arguments with science.) At most, it can dispute philosophies of science, but not discoveries themselves. It believes that Nature is like a garment of G^d. By following its operation, from the Law of Gravity to Evolution Theory, we can deduce how He operates in the world, and what situation He placed us in. (People who dispute science on religious grounds are hypocrites if they nevertheless step into an elevator and press a button without questioning the basis for its safe and predictable operation.)
To work as scientist, we do not need a religious background. We just need to be honest and smart. (Though being humble may help too.) Thus Jethro was the best for the job, to be our eyes. Tell us what things look like. Just like he advised Moses on delegating things (Exodus 18:17-23). This is not a religious law against burnout. It is psychological wisdom. But Moses elevated it into our religion (Exodus 18:24-26) because true Judaism always has all truths on board (Sayings of the Fathers 5:25). As Maimonides says: Accept truth from whatever source it comes (Eight Chapters, Introduction, point 3). Also, Do not judge a wine by its flask (Ethics of the Fathers 4:20). On Jews learning wisdom from Gentiles see: Babylonian Talmud, Megilah 9b. But we should still ask: What is this all doing in this portion? Why is this not written in the weekly portion of Jethro, where is written that Jethro went home?
In the second verse of the next week’s portion of Sh’lach, we read that prominent people will investigate the new Land. However, the Hebrew letters (with different vowels, that are not written in the Torah scroll) of “prominent people will investigate” can also be read as: “prominent people and Jethro”! May I suggest that originally the plan was that Jethro would have accompanied the spies, and, being their eyes, would have guarded them against rash interpretations of what they saw in the Land. Don’t disregard what scientists have to tell you!
One more problem. Earlier we read (Exodus 18:1) that Jethro heard [of the Miracles] while here in Numbers we read that he was our eyes. Earlier (Exodus 18:27) we read that Moses sent him off and he went to his land. But here we read that he wanted to leave and Moses tried (unsuccessfully) to argue that he should stay with the Jews. The Torah, always ready to raise questions rather than to give ready-made answers, here screams out to us: explain this contradiction. Let me try.
Seeing is more superficial than hearing, as I mention elsewhere (Genesis 3:6, Deuteronomy 6:4, 30:15). That doesn’t mean that one is more important than the other. Sometimes it’s better to stay superficial, not to worry too much while at other times it’s imperative to wonder and ponder. Jethro heard and came and heard all the deep stuff and about that, Moses had no problem to see him out so that he could go home – as written in Exodus. But at the same time (also mentioned in Exodus), Jethro saw, and for that aspect, Moses wanted him to stay because thus he could have enriched and protected us.
And that’s why Moses trying to stop Jethro from leaving is written here, as prelude to the story of the Spies. They had as task to see (Numbers 13:18) how the Land and its inhabitants are. Unfortunately, they added their own unasked-for unscientific interpretations (Numbers 13:31-33) instead of sticking to observation. With truly disastrous result.