Partly thanks to mankind's remarkable historical propensity for ignorance and violence, these are not our darkest days. But even if most of us are immeasurably better off than we were millennia or centuries ago, a passing familiarity with the strife on America's streets and depredations abroad can make the present day look dim.

And in an astronomical sense, these are our very darkest days - of the year anyway. The long nights of early winter, with fleeting glimpses of sun and months of freezing ahead, are the literally dark days from which all metaphoric meanings of the phrase spring. The closer humans are to nature - depending on the land or deprived of shelter - the more such days leave them not just downcast but endangered.

Such darkness stokes the human capacity not just for fear, but also hope. Long nights bring out candles and Christmas lights. Largely leafless landscapes still have holly, mistletoe, and pine trees.

This time of year, Judeo-Christian holidays mingle readily, and not coincidentally, with pagan-rooted customs surrounding the onset of winter. Of the symbols of light, hope, and rebirth that transcend traditions, the Christmas tree is among our most pervasive and resilient - despite its decided oddity. Some of the Americans who buy 17 million or so freshly killed trees a year no doubt pause to consider the strangeness of lashing 6- and 7-foot conifers to the roofs of vehicles, carting them along streets and highways, replanting them in suburban and urban living rooms, and adorning them with glass globes and lightbulbs. But no one hesitates long enough to slow the furious trade in this unlikely cash crop.

The Christmas tree defies much more than sober reflection - up to and including the law of the land. Take the response to Philadelphia's three-decade-old prohibition of Christmas trees in multiunit buildings: mass civil disobedience. The Inquirer reported last week that although some buildings attempt to enforce the ban - Christmas trees do present a relatively small but potentially serious fire risk - the ordinance is largely ignored by residents and officials alike.

Nor is Philadelphia's the only municipal bureaucracy that has failed to topple the Christmas-tree spirit. A large Norway spruce wrangled for display in downtown Reading was judged so ragged that the city almost consigned it to kindling. But before that happened, locals and tourists reminded of the pathetic but beloved tree of A Charlie Brown Christmas came to embrace it as a symbol of a city that is downtrodden but not defeated. So the tree stood, and the city ceremonially lit it last weekend.

In a tumultuous year that saw police officers killing and being killed, tree lightings in Philadelphia and New York collided with demonstrations. But the ceremonies and the protests - each a kind of expression of hope for better times - have gone on.

And going on, like a fir tree sucking up water well after it's been severed from its roots, is the point. Winter has come and it will be cold and dark. But already the solstice is past, and the days, imperceptibly but inexorably, grow longer.