In the Middle Ages, a new letter was assigned to this sound - J. Thus we had Iulius which was as if you said /Yulius/ or /Yulyus/. You can see this history worked out differently in the spelling systems of German and many of the Slavic languages of Eastern Europe, where the letter J spells the 'y' sound, and the letter Y, if used at all, is primarily used as a vowel.Īs mentions, this really belongs to the Linguistics group as this is a wider question pertinent to Latin and all/most Latin-influenced European languages.Ĭlassical Latin did not have a distinct J sound (the J as we know in English.) When I was followed by another vowel, it usually sounded similar to English /Y/. (English also has many sounds spelled with J which come from native Germanic roots.) So we have it that in English, the letter J now represents a consonant which is not obviously similar to the vowel, despite the fact that they descend from the same letter and the same sound. However, at about the same time there was a sound change in many of the languages of Western Europe, such that the 'y' sound changed into a 'j' sound (, or sometimes ). Subsequently, in the Latin alphabet the letter J was developed as a variant of I, and this distinction was later used to distinguish the consonantal 'y' sound from the vocalic 'i' sound. Thus, the Greek spelling for 'Jesus' was Ιησους, pronounced something like 'Yeh-SOOS', and the Latin likewise was Iesus. ) In Latin, the letter for this was I/i, in Greek it was Ι/ι (iota), and in Hebrew it was י (yod). (Just to make things confusing for English speakers, the phonetic symbol for this sound is. In the original languages (Latin, Greek, Hebrew) which provide us with the names Jesus, Joseph, Justinian, etc., the sound which we write as J was pronounced as the English letter Y.

Why that happens is a little complicated, and requires unpacking some assumptions in your question. The letter J is, as you mentioned, relatively recent, and originated as a variant of the letter I.

Old english font letter j