A poem by William Geddes (1600-1694) about the Covenant of Redemption, made between the God the Father and God the Son, and the Covenant of Grace, made between (by the mediation of Jesus) the Triune God and Mankind–the poem demonstrates how the former covenant is the ground of the latter covenant.
This is the Covenant of Grace,
Which brings my Soul so sweet solace.
There is a gracious paction
Betwixt the Father and the Son.
And by the Son, with Adam’s race,
Who should repent, and seek his grace.
The Son unto the Father spake,
I will Man’s nature on me take.
I will my self a ransom give,
For the Elect that they may live:
Come, Son, (quothe He) if thou do so,
They shall be saved from Hell and woe.
The Father to poor man he saith,
If thou believe with saving Faith,
In this my Son I’ll give thee peace:
Eternal Love shall thee embrace.
(Quoted in Joel R. Beeke and Mark Jones, A Puritan Theology: Doctrine for Life, 257-258.)