Think of the old man, waiting there in the Sanctuary, told by God that he was thus about to have the fulfilment of his life-long desire, and yet probably not knowing what kind of a shape the fulfilment would take. There is no reason to believe that he knew he was to see an infant; and he waits. And presently a peasant woman comes in with a child in her arms, and there arises in his soul the voice ‘Anoint Him! for this is He!’
And now, here He is in human nature, and good old Simeon saw Him, with his bodily eyes; a sight which many kings and prophets had desired, but were not favoured with. He see Jesus with the spiritual eye of faith, as his Saviour and Redeemer.
Many saw him in the days of his flesh, who never saw his glory, as the Son of God, and Saviour of sinners. How blessed we are to see Christ, as God's salvation, set before us, filling the soul with love of Christ, and a high esteem of him, and with joy unspeakable, and full of glory.
It transforms a soul, and makes it desirous, as it did this good man, to depart and be with Christ, which is far better than to live in this (in some sense) state of absence from him.
[Taken from MacLaren's Expositions and Gill's Exposition of the Whole Bible]