In the late summer of 1661, the Englishman Oldenburg was one of the earliest visitors to Spinoza's small house in Rijnsburg. These initial meetings, in which the two talked about philosophy and science, led to an extended and fruitful correspondence (interrupted for a time by the Anglo-Dutch war). In his letters, Oldenburg was constantly encouraging Spinoza to publish his metaphysical ideas, although as the true nature of those ideas became clearer and clearer to Oldenburg, especially after the publication of the Theological-Political Treatise in 1670, he started to have some serious misgivings about them. Writing to Spinoza some years later, in November 1675, Oldenburg takes note of those passages in the Theological-Political Treatise “which have proved a stumbling-block to readers,” especially “reasonable and intelligent Christians.” He is referring in particular, he adds, “to those [passages] which appear to treat in an ambiguous way of God and Nature, which many people consider you have confused with each other” (Letter 71).

Spinoza, naturally, is curious as to what passages Oldenburg has in mind that might appear “to undermine the practice of religious virtue” (Letter 73). In a follow-up letter, Oldenburg makes his meaning clear: