Argues that Leibniz's denial of counterfactual or transworld identity is grounded in metaphysical considerations – specifically in his belief in a coalescence of conceptual connections and causal connections, which is marked by his revival and adaptation of the Scholastic Aristotelian notion of substantial form. Exploration of Leibniz's views about miracles and about perceptual relations leads to the conclusion that his denial of counterfactual identity does not claim intrinsic metaphysical necessity, but appeals to considerations of God's wisdom and goodness; and that he can deny transworld identity only on the assumption that only aggregates of mutually harmonious substances count as worlds.
Keywords: Aristotle, counterfactual identity, harmony, Leibniz, miracles, necessity, Scholasticism, substantial form, transworld identity