Melancholy. Versus Mirth. Epiphany struck today!
But first, a story.
When I was younger, in English classes in high school, I remember being quite frustrated (I called it righteous indignation though it was more likely stubborn ignorance) that all the poetry we read, the stories that were written were so horribly depressing. The subject always had the most terrible things happen to them--whether they were abused, rejected (by) society, or slipped slowly into madness.
Being someone who enjoyed writing I was determined to be one of the successful people that wrote about happy things. Long story short...happy writings kind of stink. And if they actually had a scent they literally would. Its like the sickly, sweet smell of rotting fruit or of a dessert that is so rich your stomach reminds you that you ate it for the next 12 hours and you never want to see a pint of black raspberry chocolate chip ice-cream again in your life!! (backstory there but I'm already getting long winded so...use your imagination;). And that is where that train of understanding ended for a time.
Melancholy. That is the element I didn't get. It doesn't have to be all dismal and death but it can't just be a sugar drip either. Its like putting a pinch of salt in your oatmeal and cookie dough...the slightly polarizing contrast of that bitterness is what give genuine flavor to the sweet.
Looking at it like this, I don't see L'Allegro and Il Penseroso as two competing pieces but a starting, beginner's piece that flows into the real work, the genuine point of interest. Milton demonstrates that he can use the bits of seriousness to his advantage...otherwise L'Allegro would be difficult to take seriously. But Milton has much higher aspirations. He's building up to Paradise Lost. A supplication, an appeal to the goddess of this inspiring Melancholy seems essential, like stocking up on rations before a long summit. You better hope you've got enough and of the right kind (none of that pathological stuff) so that you'll be able to make it to the top - its a long fall to get to the top and realize you've got nothing under supporting you.
Some words in conclusion. Balance. Bitterness anchors sweetness. Sweetness strengthens bitterness. Those spots of seriousness/bitterness/pensive/melancholy would make my "happy" writings more genuine and actually ingest-able. Both mean we don't end up with a mess of sticky, sweet compost at the end.