All of the above and more. I'll start with this terza rima sonnet I wrote last winter (I hope the formatting holds--if not, it's four three line stanzas rhyming scheme ABA BCB CDC DED ending with an AA couplet):

Write to merge my soul and my consciousness

Write for expansion of my higher self

so selves integrate as one consciousness

Write so my demons remain on the shelf

and even when they escape their cages

I learn and know how to protect ourself

Write to express and temper my rages

Else my anger can turn to resentment

Progress not perfection comes in stages

Write to increase base-level contentment

Not for insane pursuit of happiness

and to avoid depths of self-contemptment

Write to share feelings and avoid numbness

and return to state of inner youngness

Douglas, your question is very timely. You mention letter writing of yore and the speed and reach of the internet age. Lately, I have engaged in correspondence between writers through our stories and comments. For example, here is one reflecting correspondence between Desiree Driesenaar and me and in which I wrote her a letter in the form of a poem: https://medium.com/write-under-the-moon/correspondence-betwixt-writers-93cb488ca689

Relationships are forming. See this piece reflecting that between Simon Heathcote and me, https://medium.com/channspirations/of-lenses-15623c1616c5 which grew out of our discussion of people view life through different lenses, which he followed up with, https://medium.com/know-thyself-heal-thyself/will-men-ever-sit-in-circle-again-7417e800ff95 , in which he called for others to participate: "I would be delighted to see other men — or women — on here add to these ideas, if they feel so called. This ball could roll!"

In the process of writing my Desiree inspired piece, I discovered an amazing letter from Steinbeck to his son which inspired this poem from me in the middle of last night (as in 3am): https://medium.com/@marcus17043/he-loves-me-he-loves-me-not-5adbd59d3cc9

Teaching is a big part of why I write. I try to teach by sharing my stories, by inspiring rather than instructing, and I guess by osmosis. I write to refine my thinking and as part of my path to an as of yet unidentified late life career change. I ran away from my old life without a new one in place. Trusting the process.

Sometimes I think I should be a book editor to pay the bills while I sort out the rest. Just putting that thought out into the universe. That's another reason I write. To emit ripples through space-time and see what reverberates.

Ok I've prattled on long enough.