If we’re heterosexual, God, nature, and evolution have conspired heavy against us in terms of what our essential function is from the age of 13 forward, which is to procreate.
But we don’t conform to this aspect of our essential nature BECAUSE WE’VE GOT BIG BRAINS, and most of us choose not to marry and raise children until the age of about 27. Our big brains desire education, sexual novelty, and other adventures, such as travel, that override our more primitive biological natures to get on with reproduction. Many of these delays in marriage and reproduction are grounded in our natural desire to seek pleasure, learning, meaning, aesthetic experience, travel, writing, public esteem, mastery of a skill, cinema, play, sports, social scenes, music, dancing, etc.
These are all fun. They’re not driven by discipline and harshness, but a longing for novelty and joy. That’s our essential nature; it’s what it means to be a young and big brained primate. It’s how God made us (if you want to put it this way). Eros, energy, and exploration are at their heights. We’re in the realm of Walt Whitman from the ages of 13 to 27.
What is therefore most essential about us as humans is our big brained creativity, curiosity, and power to drive cultural and technological evolution much, much faster than old-school evolution. This makes for difficulties keeping up. Thomistic essentializing and grousing about “the culture these days” is a tortoise chasing a speeding train.
Hence Thomism can ludicrously propose no sex–none!–and not even self-stimulation, from 13 to 27 (or longer, if you wait till your 30s to marry). It’s completely out of touch with reality, with what we are most essentially; with WHAT God made us and HOW God made us, which is by evolution building parts onto parts, and modules onto modules. Many of these parts and modules pull in different directions, and our big brains choose from among them, as from a menu of options).
So what’s essential here? Nothing. Evolution and God made one thing in the cosmos (it appears) that strongly, strongly transcends instinct and essence, and can drive evolution much quicker than biology: us.