The paper aims to look for a satisfactory ontological interpretation of the relationship between a pattern and its “elements” in D. Dennett’s ontology of patterns from the “serious essentialism” perspective by E. J. Lowe. The pattern should be interpreted as “consisting” of “lower-order patterns” which are the “modes” in E. J. Lowe’s ontology, while the pattern and its “elements” are linked by the relation of “metaphysical interdependence” by N. Thompson, representing one of the attitudes of grounding as a metaphysical explanation of a special kind. As a heuristic, a general metaphysical scheme is considered, in which elements of H. Reichenbach’s logic of the relationship between 'abstracta' and 'concreta' , which reveal themselves in D. Dennett’s ontology, such as: “reduction of the abstract to the observed”, “existence by convention” and “existence of the abstract and the observable in the ordinary world”, find an adequate interpretation within the framework of E. J. Lowe’s ontology.