QUESTION: The Gemara teaches that rain falls in the merit of those who fulfill their word. In what way is this reward measure for measure ("Midah k'Neged Midah")?
ANSWER: The YERUSHALMI (cited by TOSFOS to Shabbos 31a) explains that one who is involved in the cultivation of the land displays his faith in Hash-m. The farmer "has faith in the One above when he sows his seeds." Without rain, not only will his crop fail, but he will have wasted perfectly good food by burying it in the ground (as seeds). (This is why the verse (Yeshayah 33:6) alludes to the laws of Zera'im with the word "Emunas"; see Shabbos 31a.) When a person shows that he is faithful and true to his word, Hash-m repays him in kind by showing that He is trustworthy to send rain.
In a similar sense, rain revives one's belief in the resurrection of the dead and the World to Come. When a person passes away, his loved ones bury the body in the earth with faith that although the body will initially disintegrate, eventually Hash-m will show His faithfulness and bring the promised resurrection of the dead. "They will grow... like the grass of the earth" (Tehilim 72:16). The Midrash (Eichah Rabah 3:8) says that this faith in Techiyas ha'Mesim is the meaning of the verse, "Rabah Emunasecha" (Eichah 3:23). When one sees Hash-m's faithfulness through His rains, he becomes convinced with renewed conviction that the day will come when Hash-m will bring the dead back to life and show His power in the world. "Great is a day of rain as the day on which the dead come to life." (Adapted from "Seasons of Life," published by Targum Press.)


QUESTION: The Gemara says that "Ein Berachah Metzuyah Ela b'Davar ha'Samuy Min ha'Ayin" -- "blessing is found only in an item which is hidden from the eye" (i.e. it has not been counted). TOSFOS asks that the Gemara in Chulin (25b) says that Shedim ("demons," or forces that inflict harm) have no power to take away something which has been counted or tied in a bundle, which implies that they are able to take away something which has not been counted. Why does the Gemara here say that blessing is found only in something which is not counted?
ANSWER: TOSFOS answers that the Gemara in Chulin means that Shedim have the ability to take away only something which is Hefker, ownerless. Once something has been counted it is no longer Hefker, and thus the Shedim cannot take it. Before it has been counted, Hash-m gives a blessing to the item so that it increases, as the Gemara here says. The increase itself is Hefker (until it is noticed by the owner when he counts his objects). That extra bit can be taken away by the Shedim before it is counted. By not counting one's produce, one makes it possible for his produce to increase as a result of Hash-m's blessing. That extra produce is then vulnerable to harm from the Shedim, for it is Hefker until it is counted.
The KAV HA'YASHAR explains the first verse of Birkas Kohanim (Bamidbar 6:24) based on this approach. "May Hash-m bless you" -- the concept of "blessing" refers to increase and proliferation, or "Ribuy" (Rashi to Sotah 10a, DH ba'Meh Bircho). The next phrase in the verse is, "And may He protect you," which the Sifri (Naso 40) explains to mean "may Hash-m protect you from Mazikin (Shedim)."
Since the first part of Birkas Kohanim contains a request that Hash-m give us bountiful blessing, there is concern that the extra increase that He gives will have the status of Hefker which the Mazikin are able to damage. Therefore, the blessing continues with a request that Hash-m protect us from the Mazikin.