But the sharing impulse is year-round, so much a part of our communities that it's background noise.
People are tutoring in schools, cleaning up parks and rivers, building playgrounds, running PTAs, guiding museum tours, comforting folks at hospitals, mentoring young adults, visiting nursing homes, coaching Special Olympians.
They serve on school boards and town councils and on boards of charitable organizations. People are riding bicycles, running 10Ks, walking long distances to fight disease and suffering. People are carrying lasagna to the grief-stricken and hauling outgrown clothes to nonprofit thrift stores.
People are building houses, planting trees, fighting fires. And they are opening their checkbooks, their PayPal accounts, their Google Wallets: last year, Americans donated a record $410 billion to charities, according to Giving USA.
This urge to pitch in knows no age, no race, no gender, no income level. And refreshingly, no politics.
I think we face two kinds of problems in this world: forever problems and right-now problems. Forever problems are those persistent challenges, vast and complex, that humans confront but seldom solve. They touch so many facets of our nature and the social order, and are so entangled with one another, that they transcend the personal to become political.
Take, for example, the distribution of wealth. Some people have hardly any money; others have unimaginable mountains of it.
Versions of this reality have perplexed the world for ages, and it remains a defining political question for 21st-century Americans.
Some see it primarily as a problem of educational opportunity. Some see it as a matter of taxation. Some see it as a question of corporate control. Some see it as a matter of family structure. Some see it as a manifestation of greed - a moral failing. Some see it as a manifestation of slow growth - an economic question.
It is safe to say that when the public can't agree on the cause or even the definition of a problem, we're not on the brink of a solution. There's a reason we can read of this problem on papyrus scrolls and in medieval libraries, in Dante, Shakespeare, Dickens and Toni Morrison: It is a forever problem.
In Matthew's account of his ministry, Jesus said: "The poor you will always have with you." Despite centuries of thought and hard work, of debate and revolutions, that forecast remains accurate.
Timely access to effective and affordable health care seems to be another forever problem. So, too,is the education young people need to build happy, productive lives.
Much of what we hear our politicians and pundits arguing about week in and week out is entangled in forever problems. They are thorny and frustrating and often divisive. Their very complexity invites oversimplified answers and lines in the sand.
The politics of forever problems give us the feeling that the nation is hopelessly divided, impotent, and helpless in the grip of our challenges.
But as much as forever problems push us apart, right-now problems tend to bring us together. These are the human-scaled, ground-level vicissitudes of life, and though we cannot erase them, we routinely pitch in to soften their edges without a moment's thought about political differences.
We may not be able to agree on the future of health care, but give us a family down the street with cancer in their midst, and we'll figure out how to get meals to them during chemo.
As the man said: There are a thousand points of light. So let us not be discouraged by the difficulty of forever problems, but in seeking their solutions, may we draw on the goodwill of the bellringers, the child comforters, the feeders of the hungry, the soothers of the sick.
They aren't the noisy ones, but you can find them on every boulevard and in every burg. Ad hoc and undirected, they face the right-now problems with a unifying resolve. They are the glue, and the glory, of our persistently imperfect human society, the better angels of our nature taking wing.