The title refers to the sibling rivalry between Jacob and Esau in the Jewish and Christian Bible, and comes directly from Malachi 1:2,3: "Jacob have I loved, but Esau have I hated."
Later, philosopher Miguel de Unamuno, Machado's contemporary, developed the idea through the Biblical story of Jacob and Esau struggling for dominance in their mother's womb, as in the article "Rebeca" (1914), which may pre-date Machado's quatrain.
Many ancient Hebraic names that have not been found in other Near Eastern languages have been reported to occur in similar forms in Eblaite (Adamu, H’à-wa, Jabal, Abarama, Bilhah, Ishma-el, Isûra-el, Esau, Mika-el, Mikaya, Saul, David, et al.
In 1399 Esau, supported by some Albanian clans, marched against his wife's brother-in-law Gjon Zenebishi of Gjirokastër.
Leonard Esau Baum was an American mathematician, known for the Baum–Welch algorithm.
Esau Mwamwaya was born in Mzuzu, Malawi, but grew up in the capital, Lilongwe, where he played drums in various bands.