"deeper subjects" is correct and usable in written English.
You can use it to refer to topics that require a deeper level of understanding or analysis. For example, "The course focuses on deeper subjects, such as international law and economic history."
Swift writes mostly about love, but her deeper subjects are image, narrative, and power; her work and her career present an exploration of how a young woman might turn one into another, and approach the top.
"Nightline" producers have defended Mr. Koppel's anchor schedule of three nights a week by saying it allows him to pursue weightier, deeper subjects, like the civil war in Congo, while his substitute, Chris Bury, holds down the fort.
Deeper subjects, such as his fears or family issues, may mean that he wants to take your relationship with him to a deeper level.
Luckily, Dante's present is infused with the past, and the book is ultimately saved by its deeper subject matter.
Her immediate topic was pesticides, but her deeper subject was human arrogance — the delusion that altering the world means controlling it.
Though this book records an expatriate American's obsession with pianos -- their history and playing -- its deeper subject is his engagement with France.
"The changes we are making will restore confidence in GCSEs … they will be more rigorous, with deeper subject content and match the best equivalent exams in the world".
Moving into even deeper subject matter in Darren Aronofsky's The Fountain, Jackman starred as a scientist desperately searching for a cure for brain cancer while his wife, played by Rachel Weisz, is slowly consumed by a tumour.
The 10 finalists were quizzed on very deep subjects, like their pet peeves and whether they were morning or night people.
Would we walk the streets for hours, talk about deep subjects and learn new things about each other?
In black and white, the original 53-minute interview hits deep subjects like politics and mercy killings.
