“Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you. For everyone who asks receives, and the one who seeks finds, and to the one who knocks it will be opened.” (Mat 7:7-8, ESV)
There is a difference between what the brain (intelligence/mind/reasoning) knows and what the spirit (heart/soul/gut) knows, and only the former can be satisfied with theories and facts alone. The brain does not need experience in order to know, only exposure. But the brain does not digest.
The spirit, however, is the one who asks, seeks, knocks. This activity prepares us to receive, to experience, and to digest. What the spirit knows is given, a gift, a blessing, a grace. It is not there for the taking.
Depth is more than just knowing facts or espousing theories. Therefore the above Scripture passage does not teach answers, findings, what is behind the door. It invites us to experience what will be given when we ask, seek, knock. Depth comes from, and with, experience of that which is real and true.
If someone asked me what people lack most these days, my answer would be “Depth”. See ye here room for improvement.