In the midst of current debates over the precise relationship between the pre-lapsarian Covenant of Works and the Mosaic Covenant, it would do us good to remember that many of the Reformed theologians of the 17th, 18th, and 19th Centuries understood that the Law given at Sinai, with its promise of blessing and cursing in accord with its subsequent demand for perfect obedience, was  the reflection of the Covenant of Works. Because of developments in Covenant theology in the 20th Century in the writings of  Meredith Kline and John Murray, many have neglected to see the categorical relationship between the two. Geerhardus Vos, who some appeal to as rejecting such a relationship, made the following observation:

We can also explain why the older theologians did not always clearly distinguish between the covenant of works and the Sinaitic covenant.  At Sinai it was not the ‘bare’ law that was given, but a reflection of the covenant of works revived, as it were, in the interests of the covenant of grace continued at Sinai.1