As the prophets from the beginning have declared concerning him (1)

For the good of your own soul drink in the deep theology of the Chalcedonian Definition (451 AD):

Therefore, following the holy fathers, we all with one accord teach men to acknowledge one and the same Son, our Lord Jesus Christ,
at once complete in Godhead and complete in manhood,
truly God and truly man,

consisting also of a reasonable soul and body;
of one substance with the Father as regards his Godhead,
and at the same time of one substance with us as regards his manhood;
like us in all respects, apart from sin;

as regards his Godhead, begotten of the Father before the ages,
but yet as regards his manhood begotten, for us men and for our salvation,
of Mary the Virgin, the God-bearer;

one and the same Christ, Son, Lord, Only-begotten, recognized in two natures, without confusion,
without change,
without division,
without separation;
the distinction of natures being in no way annulled by the union,
but rather the characteristics of each nature being preserved and coming together to form one person and subsistence,
not as parted or separated into two persons,
but one and the same Son and Only-begotten God the Word, Lord Jesus Christ;

even as the prophets from earliest times spoke of him, and our Lord Jesus Christ himself taught us, and the creed of the fathers has handed down to us.

As well as contemplating the boundaries of this mystery do note the authoritative source of these truths. And do not overlook the fact that this definition sees the whole Bible as foundational for the doctrine of the person of Christ, and not just the New Testament.

This should not surprise us. Abraham saw his day and rejoiced (John 8:56), Moses wrote of him (John 5:46) and "considered the reproach of Christ greater wealth than the treasures of Egypt" (Heb. 10:26), David called him Lord (Psalm 110:1 and Mark 12:35-37), Isaiah saw his glory in the temple and spoke of his sufferings (John 12:41 and Isa. 52:13-53:12), and as Peter explained to Cornelius and his household "To him all the prophets bear witness that everyone who believes in him receives forgiveness of sins through his name" (Acts 10:43).

But perhaps it does surprise us. We live on the other side of the Enlightenment to the early fathers, medieval scholastics, the reformers and the puritans.

Moreover the patriarchs and the prophets met the Son of God, the chief Actor in the drama of redemption before he entered the stage to play out the climactic scenes that their script was intended to describe.

They gave advanced screenings of those climactic scenes, as Sibbes wrote about the prophecy of Isaiah in The Bruised Reed:

The prophet Isaiah, being lifted up and carried with the prophetical spirit, passes over all the time between him and the appearing of Jesus Christ in the flesh. Seeing with the eye of prophecy, and with the eye of faith, Christ as present, he presents him, in the name of God, to the spiritual eye of others...