كَالْجُزْءِ مَعَ الْكُلِّ وَالصِّفَةِ مَعَ الذَّاتِ
Like a part in relation to a whole and an attribute in relation to its subject.
Part and whole are not synonymous concepts, yet they stand in a special relation. The analogy illustrates that a conceptual distinction does not always entail two complete independent beings.
The analogy has a strict limit: God's essence is not a material composite of parts. The example illuminates the logic of relational language; it is not a claim that the divine essence is assembled from components.