Every Tzaddik Holds a Portion of Moshiach

In a maamar for 22 Tammuz, the hillula of Rav Shlomo of Karlin, Rav Aharon taught that Hashem sends tzaddikim in every generation who suit that generation, and each generation suits its tzaddik. When a tzaddik comes back to this world, it is not because he failed at something. Each tzaddik repairs the middos and levels connected with the reason he came into the world. On account of the tzaddikim, Moshiach could already have come, but Hashem alone knows that not all the attributes have yet been completed. So each tzaddik holds a portion of Moshiach, according to the trait he repairs. This explains why the Gemara says that Moshiach's name is Chizkiya, Yannai or Menachem, and why the Ohr HaChaim HaKadosh said that it is Chaim: each of them completed his own portion, and each spoke the truth. All are the words of the living G-d.