Edwards on the Gospel in the Old Testament

From his History of the Work of Redemption:

Some are ready to look on the Old Testament as being, as it were, out of date and as if we in these days of the gospel had but little to do with it; which is a very great mistake, arising from want of observing the nature and design of the Old Testament, which if it was observed it would appear full of the gospel of Christ, and would in an excellent manner illustrate and confirm the glorious doctrines and promises of the New Testament. Those parts of the Old Testament which are commonly looked upon as containing the least divine instruction are, as it were, as mines and treasures of gospel knowledge, and the reason why they are thought to contain so little is because persons do but superficially read them. The treasures that are hid underneath are not observed.

--Jonathan Edwards, A History of the Work of Redemption, in The Works of Jonathan Edwards, Yale edition, vol. 9, 290