 One way to understand logic is as the study of the most general forms of thought or judgment, what we called (L4). One way to understand ontology is as the study of the most general features of what there is, our (O3). Now, there is a striking similarity between the most general forms of thought and the most general features of what there is. Take one example. Many thoughts have a subject of which they predicate something. What there is contains individuals that have properties. It seems that there is a kind of a correspondence between thought and reality: the form of the thought corresponds to the structure of a fact in the world. And similarly for other forms and structures. Does this matching between thought and the world ask for a substantial philosophical explanation? Is it a deep philosophical puzzle?