Expectation of the Messiah and his Spirit
The characteristics of the awaited Messiah begin to appear in the "Book of Emmanuel" ("Isaiah said this when he saw his glory," speaking of Christ), especially in the first two verses of Isaiah 11:
There shall come forth a shoot from the stump of Jesse,
and a branch shall grow out of his roots.
and the Spirit of the LORD shall rest upon him,
the spirit of wisdom and understanding,
the spirit of counsel and might,
the spirit of knowledge and the fear of the LORD.
Source: Catechism of the Catholic Church (Vatican.va)