The Surprising Evolution of LE > SE in Spanish
[Para español, ver abajo.] In Old Spanish , indirect object pronoun "le" (to him, her, you plural), when put together with direct object pronouns lo(s)/la(s) in the combination lelo/lela , evolved phonetically and naturally, first to diphthong lie(lo) > lle(lo)> gelo (g was pronounced like French j or s in measure), and finally to present day se lo or -selo . Note that this se only looks like reflexive se as in Mi mejor amigo se levanta a las 5 de la mañana , but its function is completely different. That's why, nowadays, we say se lo doy (I give it to him, her, you singular, you plural or them) or dáselo (give it to him, her, you, you all, them). Old Spanish: gelo do (se lo doy). If the context is not sufficient, people specify by adding on: descríbeselo a él, a ella, a ustedes, a ellas, a mi amigo, al profesor, etc. If you speak Italian, you'll notice a similar evolution happened to arrive at " glielo do " (se lo doy). -----------------------