What is the significance of the four rivers that branched off the river that came out of Eden and watered it?
Ramban (in 3:22): The four rivers are symbolical of the four nations (Bavel, Madai, Yavan (Greece) and Rome) that subjugated Yisrael in the course of history.
Seforno: Although we know nothing about the Garden of Eden, the Torah tells us the praise of the river by mentioning the names of the four tributaries that branched off it - rivers that are known for their size, and for the quality of their water and their fruit.
What is the significance of the River Pishon? Why was it called by that name?
Rashi: It is synonymous with the River Nile, and is called "Pishon" because its water is blessed inasmuch as it rises and waters the surrounding land; 1 or because it grows flax (Pishtan). 2
Rashi: As the Navi wites in Chavakuk 1:8.
Rashi: As the Navi writes in Yeshayah 19:9, in connection with Egypt.
Of what importance is it to know that gold was to be found in the Land of Chavilah?
Ramban: It is to teach us that the land of Chavilah mentioned here is not the one close to Egypt (that is mentioned in 25:18 as being close to Egypt), but is the land in the far east called India (as Targum Yonasan explains). That is the area that contained high-quality gold, crystal and onyx-stones.
Rashi (whom the Ramban quotes): Chavilah is synonymous with the Chavilah mentioned in 25:18. Indeed, one of the reasons the River was called 'Pishon' is flax (Pishtan), for which Egypt was famous, grew there. 1
Rivash, Chizkuni: Two different nations would be known as Chavilah; a son of Kush, descended from Cham (10:7), and a son of Yoktan, from Shem (10:29). Which of their two regions is this Pasuk referring to? Many verses speak of gold imported from the land of Ofir (e.g. Divrei ha'Yamim II 9:10), and Ofir was a son of Yoktan (10:29). The Torah mentions gold in order to specify that the Chavilah it refers to was of the son of Yoktan.
Many other major commentaries subscribe to this explanation.
QUESTIONS ON RASHI
Rashi writes: "'Pishon' - The Nile, so called because its waters rise and spread...." Why does Rashi offer explanations for the names of these rivers?
Gur Aryeh: Rather than simply writing, 'The first was Pishon...,' the Torah writes "The name of the first was Pishon." Rashi infers that we should derive the meanings of these names.
