“Let My Teaching Drip Like Rain...” (32:2)
In the song of Ha’azinu, Torah is described as both “rain” and “dew” (v. 2). Physically speaking, rain and dew are both sources of nourishment, but the causes which bring them about differ significantly. Rain is formed from water which is lost to the atmosphere as vapor from the earth, then condenses and precipitates back—as the verse states:“a mist ascended from the earth, and then soaked the entire surface of the ground” (Bereishis 2:6). The precipitation of rain is thus dependent on prior evaporation from the earth.
Dew, by contrast, “never ceases” (Ta’anis3b), and appears spontaneously, regardless of the amount of water which is being evaporated from the earth.
Rain thus represents the influx of Godliness which is bestowed from above, in direct response to the efforts of Man (on earth). Dew, on the other hand, alludes to that which God bestows unconditionally, disproportionately to man’s efforts.
So, since “rain” and “dew” in this verse both refer to Torah, it follows that “rain” represents the parts of Torah which are dependent on the degree of effort on the part of man to master them—namely, the extensive legal discussions of the Torah. The comparatively effortless “dew” alludes to the mystical parts of the Torah, which transcend the limitation of the human mind, since they “flow” directly from their Divine source (as the verse states, “Let my words flow like dew”).
Consequently, we find it is the “dew” of Torah with which God will ultimately revive the dead (and not the “rain”), since “all Jews” will enjoy resurrection and “have a portion in the world to come” (Sanhedrin 90a). And clearly, something that is bestowed upon all Jews, regardless of their spiritual standing, must be given from Above, like dew, regardless of the efforts made to elicit it.
(Based on Sefer Hama’amarim Melukat vol. 1, p. 458ff.)