Full Idea
Locke's thesis about persons implies that, whenever I have a thought, two thinkers have that thought: me and 'my' thinking substance.
Gist of Idea
Locke implies that each thought has two thinkers - me, and 'my' substance
Source
comment on John Locke (Essay Conc Human Understanding (2nd Ed) [1694]) by Trenton Merricks - Objects and Persons §2.IV
Book Reference
Merricks,Trenton: 'Objects and Persons' [OUP 2003], p.48
A Reaction
Although Locke asserts the existence of a distinct entity, the 'person', he is fairly vague about the ontology involved. Some have suggested that he is a functionalist, and we could say that the substance 'constitutes' the person.