intellectual depth; penetrating knowledge; keen insight; etc; "the depth of my feeling"; "the profoundness of the silence"
Profundity is great intellectual depth and understanding. The profundity of this book is achieved with breathtaking lightness. = depth, shallowness
If you refer to the profundity of a feeling, experience, or change, you mean that it is deep, powerful, or serious. the profundity of the structural problems besetting the country
A profundity is a remark that shows great intellectual depth and understanding. His work is full of profundities and asides concerning the human condition. banality