As is well-known today, there are two types of twins – identical (monozygotic) twins and fraternal (dizygotic) twins. As a rule, non-identical twins develop in separate placentas. Clearly, Esav and Yaacov were fraternal twins, and in that case, how is one to understand the Torah’s assertion that Yaacov grasped Esav’s foot? Did his tiny hand actually break through both placentas and grab the foot? If so, this must have been a truly fascinating occurrence – and it is no wonder that it caught the attention of the midwife (or whoever was present at the birth) and was apparently memorialized in Yaacov’s name! Thus on the verse (Bereishith 25:26): “and his hand was holding the foot (עקב) of Esav, and he called his name Yaacov”, Rashi comments: His father called him Yaacov on account of the holding of the foot.
However, Rashi first explains that when the verse says “he” called his name Yaacov, it is referring to Hashem. That is, Hashem named him Yaacov. But, here, Rashi does not give the basis for the name! R. Yosef Colon (מהרי”ק) therefore suggests (based on the usage of the root עקב in Job 37:4) that on this approach, the name means “he who will outlast” (see also Tosafos Nazir 22b s.v. אמרה) – alluding to the fact that in the end of days, the descendants of Jacob will supplant the descendants of Esav as leaders of the world. Indeed, Rashi (s.v. בעקב עשו) explains the symbolism of the holding of the foot to mean that at some point (the descendants of) Jacob will take the leadership away from (the descendants of) Esav.
A different – and offensive – interpretation of Jacob’s name is given by Esav. On discovering that Yitzchak has given Jacob the blessing intended for Esav, the latter remarks (Bereishith 27:36): “Indeed, this is why he was called Ya’acov, for he has cheated me twice, he took my birthright and now he took my blessing”. Here the root עקב means “crooked” as in Kings-II 10:19 and Jeremiah 17:9 (Ibn Ezra). [According to Rashi (following Onkelos), it means “to outwit” or “to trap”.]
So, Ya’acov’s name is a double-edged sword that can be construed as a blessing or as an insult. Similarly, Rambam (Epistle to Yemen) explains that the Divine promise “your seed shall be like the dust of the earth” (Bereishith 28:14) has a double meaning: even though the Jewish nation is lowly, and trampled upon by all the nations (i.e., they are like dust that is trampled on) – they will in the end survive, endure, and be victorious over all their enemies (i.e. like dust that remains long after those who trampled on it have expired). Moreover, just as the dust eventually covers those who trample upon it, so too will Israel outlive its oppressors.
Curiously, the Gemara (Berachoth 13a) states that even though Ya’acov is eventually renamed Yisrael (Bereishith 32:29, 35:10), this name does not replace the original name, but is added to it. If, as above, Hashem himself named Jacob as Ya’acov, this makes perfect sense. But what is the point of adding another name?
The answer would seem to be that the name Yisrael reflects the blessing inherent in the name Ya’acov. For you have striven… and prevailed (Bereishith 32:29). That is, Ya’acov can be trodden by the heel of Esav, but can also outwit, outsmart, and outlast Esav. Essentially, this is Ya’acov’s historic challenge: to make it clear to all that Ya’acov is Yisrael. The one who endures, the one who outlasts all others, the one who in the end prevails.