What’s Jacob got to do with Diego?
Decades ago, I first came across the name Diego. Unlike numerous Spanish names that have a readily recognizable cognate in English, Diego seemed solitary in the “namescape”. Unlike Alejandro–Alexander, Matías–Matthew, Lucas–Luke, Andrés–Andrew, Juan–John, José–Joseph, … Diego stood like an island, separated from the rest. Years later, the mystery slowly began to shed its shroud when I discovered that Santiago was an alternative form of San Diego. Phonetically, I could see the similarity between Tiago and Diego, but that just made me wonder even more where they both might have originated. Finally, when someone mentioned to me that Diego and Tiago were Spanish equivalents of James, my linguistic curiosity was piqued. Sometimes additional information only leads faster to a dead end, I thought. After all, people can make wild claims about anything. But sometimes the truth surfaces in unlikely places.
Years later, I came to wonder how the name James could have been derived from Jacob. The first key to the answer came to me through the Italian forms for these names, some classic and some modern. Iacobo, Iacopo, Giacomo: we know that these names hark back to the Biblical name of Jacob — “Ya’kób” in Ancient Hebrew. Starting from the original Ya’kób, it is easier to show how it slowly mutated into its various forms in European languages. The Hebrew name was transliterated in the Greek New Testament as Iakóbos (I sounding like Y), a form quite close to the original. From Greek to Latin, little changed in going from Iakóbos to Iacobus (c sounding like k). Over the centuries, as Latin branched into the modern Romance languages, Iacobus also evolved into new forms. We will follow the Italian branch, in its various stages, because it allows us to trace this evolution most clearly. Over the centuries, Iacobus became Iacobo, then sometimes Iacopo or Iacomo, until the initial Ia (sounds like Ya) started sounding like Ja, as the modern Italian spelling of Giacomo attests. It is not difficult to see a connection between Giacomo and Jacob, but where does James come from? We can at least see that both Giacomo and James share an m. The closest phonetic connection can be observed in Portuguese Jaime which developed from Late Latin Iacomo, losing the co somewhere along the corridors of the centuries.
So, how do any of these details help us lift the shroud off Diego and Tiago? The key to making sense of these names is to lay them alongside San. Let us go back to Latin and put the word for Saint before Jacob: Sanctus Iacobus. As the Latin language travelled through the ages, Sanctus Iacobus eventually turned into Sanct Iacob. In Spanish, it further evolved into Sant Iacob, which fused into Santiacob before dropping its final b and changing c (sounding like k) into g, yielding Santiago. The resemblance of Iacob to Iago remains evident, but time further clouded this once-clear picture. As Spanish matured into its modern form, the prefix of San was paired with the names of male saints, while Santa was fitted to the female names, as evidenced in San Agustín, son of Santa Mónica. For male names, Latin Sanct was whittled down to Spanish San, dropping the final c and t, in most cases. In Spanish, Saint Jacob had survived in two combined forms, Santiago and Sandiego, that retained a vestige of the final t in sanct. The process of splitting Santiago and Sandiego right after the n clearly demonstrates that the speakers of Spanish, at the time, did not regard the t (or d) as possibly belonging to the prefix San. The splitting gave birth to Tiago and Diego by a simple, intuitive dropping of San. These newly derived names can be verified at least as far back as the 1500s, as evidenced by the famous painter, Diego Velasco. In the same era, Shakespeare was aware of Iago as a name, and even bestowed it on the main foe in his play, Othello. Although it took a few centuries to spawn Diego and Tiago from Jacob, today, these names continue to live alongside other related forms such as Jacobo and Jaime.
Just as the flowing stream slowly rubs the pebble smooth, so only can the human tongue reshape Jacob into Diego.
