Final answer:
The statement is False. John Locke defined the ontological concept of substance as "a something, I know not what."
Step-by-step explanation:
The statement is False.
John Locke defined the ontological concept of substance in his work Essay Concerning Human Understanding. He described substance as "a something, I know not what." However, it was Scottish philosopher David Hume who proposed a secular concept of self in response to empiricist thinkers' views on substance and knowledge. Hume's thoughts on substance and self were influenced by Locke's ideas.