Standing at the top of the steps looking out for the messiah as he did every day, Simeon has taken to even checking out babies. Earlier, he must have thought that the messiah would come riding in on a white horse with an army following, but more and more, Simeon's vision has been shaped by the study of scripture. Mary and Joseph come to the Temple carrying their newborn child. And before Mary can protest, the old man has gathered Jesus up in his arms. He must have asked the parents questions about their journey, where they were staying, and who they were.
Every detail seems to be confirmed.
He cannot help himself. Simeon announces that as impossible as it may seem, the Messiah has come. If there is anyone in Jerusalem who has adequate wisdom to recognize the messiah, it is Simeon. He sings a canticle of praise and thanksgiving. An oracle is the prophesy, the prophesy is of pain.