In "Frost at Midnight," Coleridge is concerned with one specific family member: his infant son, Hartley Coleridge. Everyone else is asleep in the cottage, and Hartley is the only person in the room with Coleridge, as his thoughts bounce around, gradually concluding in his high hopes for Hartley. Specifically, he wants lil' H. to grow up close to Nature, having the kind of spiritually-inspired childhood Coleridge wanted to have (but didn't, because he had to go to school in London). Also, Coleridge reflects on how he wished different family members (like his sister, Ann) would pay him a surprise visit while he was stuck in school. We know: isn't that sweet?
Family is the most important thing to Coleridge, even more important than Nature.
Actually, Coleridge is just "using" poor lil' Hartley here. His real focus is on Nature; his son is just a hook to get us interested in the natural world.
Smile, folks. Happiness is a huge part of Coleridge's poem. For him, it needs to have a spiritual solution. Genuine joy comes with encountering God in Nature. It's not something that comes from playing Grand Theft Auto VIII, or blowing up aliens' heads in a virtual reality simulator (though plenty of people would beg to differ). Coleridge reflects on the roots of his own unhappiness and melancholy—his distance and alienation from Nature in his childhood—and hopes that his son will find a pathway to something better. Ultimately, happiness doesn't come from exerting your willpower over people or desiring more distractions. Rather, in Coleridge's view it comes from appreciating reality and from cultivating personal relationships with friends and family.
Despite his efforts to convince us otherwise, it's pretty clear that our speaker isn't a happy person.
The fact that he can recognize and name a true source of happiness (the natural world) is an indication that our speaker is more authentically happy than most (expect, you know, maybe Pharrell).
Sure, it sounds bad, but isolation isn't really a bad thing in "Frost at Midnight." A better term might be "solitude." By being alone at night (except for his sleeping baby) Coleridge is able to attain deep insights, while reflecting on his past, his relationship with Nature, and his baby's future. He wishes for his son to experience solitude in Nature, but that won't really be solitude, since his son will be able to sense God in Nature, to feel a sense of companionship when he seems to be isolated.
Coleridge is not truly alone in this poem, and he doesn't truly feel that isolation is anything worth pursuing.
Coleridge's love of Nature is really just a way for him to escape his fellow man, drop out of society, and be totally alone in the world.
In "Frost at Midnight," Coleridge views Nature as a source of wisdom for humanity. What he wasn't able to find in his boring classroom, he thinks his son will be able to find in Nature. Humans have made everything in the city, but God has made everything in Nature, which, in Coleridge's view, makes it a superior source of instruction and knowledge. Even if something in Nature seems unpleasant or weird or mildly creepy or hostile to life—like the frost, arguably—it is still testifying to God's creative power. Since God has "all things in himself," says Coleridge, people should be able to find evidence of God in all things.
With the rise of human civilization, the Natural world is just an invention, an idea spread though works of art like this very poem.
Oh, really? Try this on for size: there can never be a real separation from Nature. This poem shows us that, even in the supposed confines of human civilization, humanity is smack dab in the middle of the natural world.
Coleridge is deeply religious, but—thanks to his opium addiction and his other difficulties (like his unhappy marriage)—he thinks he hasn't fully lived up to his spiritual ideals. (Opium addiction will do that, you know.) He's hoping that his son will live up to his own lost promise and have the kind of spiritually-fulfilling life that he hasn't really been able to appreciate. God is, in Coleridge's eyes, wholly loving and benevolent. He wants human beings to enter into a relationship with him. In "Frost at Midnight," Coleridge is hoping that Nature provides the key to developing that relationship.
This poem is actually evidence that Coleridge is having a spiritual crisis of faith.
This poem shows us that all love of Nature is really a spiritual love for a higher power (deep, eh?).