Full Idea
Spinoza held a bundle theory of the mind, according to which our mind is but a bundle 'composed of a great many ideas'.
Gist of Idea
Spinoza held that the mind is just a bundle of ideas
Source
report of Baruch de Spinoza (The Ethics [1675], II Pr 15) by Stephan Schmid - Faculties in Early Modern Philosophy 3
Book Reference
'The Faculties: a history', ed/tr. Perler,Dominic [OUP 2015], p.171
A Reaction
This seems to imply that the mind lacks unity, and also lacks a Self. Spinoza doesn't say much about this view.