They were published in Germany and in England soon after the correspondence ceased and became one of the most widely read philosophical books of the 18th Century. Spinoza justifies this move defensively; at E1P10s Spinoza claims that nothing we know about the attributes entails that they must belong to different substances, and consequently there is nothing illegitimate about claiming that a substance may have more than one attribute.
But what is the character of these non-actualized possibles? Answer: for the moral evaluation taking place in the divine intellect.
It is probably most helpful, then, to see Leibniz's philosophy as a reaction to two sets of modern opponents: on the one hand, Descartes and his followers; on the other hand, Hobbes and Spinoza.
PII Now, it was said above that Leibniz excludes purely extrinsic denominations or relational properties from the kinds of properties that are constitutive of an individual.
There is, however, a common way to reconcile the two views: the Divine Choice Theory literally explains the origin of this world, and the Striving Possibles Theory is merely a metaphor. Indeed, according to Leibniz, animals operate not as mere automata as they do in the Cartesian philosophy, but rather have fairly sophisticated mental faculties.
Thus, even in a deep and dreamless sleep, the mind is active, and perceptions are in the mind. However, Leibniz may have a point in arguing that it would be absurd in some sense for an infinite being to choose anything other than an infinitely rich and thus perfect universe.