Rachel wants some dudaim (possibly "mandrakes") that Reuben's son Leah gathered, and barters them for a night with Jacob (which Leah uses to produce yet another son). (Gen. 30:14-19).
Why does Rachel want the mandrakes? The conventional wisdom, as enunciated by R. Hertz, is that the mandrakes are some sort of "love-charm."
Ramban disagrees; he cites Ibn Ezra's statement that the mandrakes "have a good odor" and suggests that Rachel wanted them for that reason.
What about the idea that the mandrakes are somehow an aid to pregnancy? Ramban writes: "I have not seen in thus in any of the medicinal books discussing mandrakes."
This illustrates one argument within Judaism: to what extent is secular knowledge important? Ramban clearly believes that secular knowledge (in this case, medical knowledge) is important because it helps us understand the Torah.
Of course, this is an easy case; more difficult questions are presented by knowledge less obviously relevant to the Torah. What about history? Philosophy? Some would argue that these disciplines are likely to contradict the Torah, and thus best ignored.
On the other hand, it seems to me that if these disciplines appear to contradict the Torah, perhaps it is the case that neither history nor Torah is wrong, but that we have interpreted the Torah too literally, or otherwise misunderstood it. The Karaites may have interpreted the Torah literally*, but the rest of us have never done so.
*Or at least so their critics claimed.
