Sometimes Hobbesian ideas have what we might call conceptual parts. One example is the discussion of resolution in De Corpore 6.4. The idea square is said to have parts including line and angle, and the idea gold is said to have parts including solid and heavy.
At other times, though, the parts of ideas seem more like the spatial parts of images. One example of this occurs when Hobbes talks of remembering, and the ways memories are less detailed than experiences, in Elements of Law 3.7. This he describes as involving a “missing of parts” and a lack of “distinction of parts”. So on the one hand you look at a city and see the buildings clearly distinguished, on the other you remember it as “a mass of building only”. But here the parts that are missing, or can’t be distinguished, are spatial parts of the image.
I don’t know what to make of this. But I think Hobbes is not alone, among philosophers with a more or less imagistic theory of ideas, in having these two sorts of parts in mind. So Hume usually thinks of ideas as having conceptual parts. But in Treatise 1.2, in the discussion of space, the coloured points into which our visual impressions and ideas are resolved are spatial rather than conceptual parts.
[Cross-posted from modsquad.)