We humans sometimes don’t know what we’re seeing and often don’t know what we’re hearing and saying.

Abandoned by its mother.

A couple of weeks ago, this bird’s egg suddenly appeared on the railing outside the dining-room window at Mitchell cabin. Although Lynn was sitting at the dining-room table, she didn’t see the bird that laid it, but the egg couldn’t have been on the railing very long. The day was windy, and shortly after I snapped this picture, the egg was blown off the railing and broke.

I later showed this photo to Dave DeSante, president of the Institute for Bird Populations in Point Reyes Station, but he couldn’t identify it. “Too many birds have white eggs like that,” he said.

Nor would he hazard a guess as to what the egg had been doing on my railing. My own SWAG (military parlance for “scientific wild-ass guess”) is that some bird went into labor before she could make it back to her nest.

Another mystery: Why is the National Rifle Association, which is dominated by southern white men, now fighting against federal gun-control legislation.

People need to be armed, they claim, to protect themselves from not only criminals but also from oppressive government.

The NRA seems to forget that in the 1960s, it helped draft some of the early gun-control laws. What has changed?

During the Civil Rights Movement, armed Black Panthers began patrolling the streets of various cities to protect blacks — sometimes from abuse by police.

On May 2, 1967, when Ronald Reagan was governor of California, he chanced upon a group of armed Black Panthers at the state capitol. Reagan became so frightened that he took off running and despite his political conservatism immediately began advocating gun-control legislation and garnered support from the NRA.

It sounds to me as if the way to get gun-control legislation passed is to bring back the Black Panthers.

Here’s an expression we hear all the time, but few people know its origin: “Leave no stone unturned.”

The expression, according to the Morris Dictionary of Word and Phrase Origins, “goes back to a battle between forces led by the Persian general Mardonius and the Theban general Polycrates in 477 BC.

“The Persian was supposed to have hidden a great treasure under his tent, but after he was defeated, the victorious Polycrates couldn’t find the valuables. So he put the question to the oracle at Delphi (above left) and was told to return and leave no stone unturned. He did — and found the treasure.”

A “girl” in the Middle Ages: is the child really male or a female? Hard to tell. And, no, the kid’s not a hermaphrodite.

As the Morris Dictionary explains: “It seems hard to believe that in the Middle Ages [the 5th to the 15 century] a girl could be a young child of either sex.

“Indeed, such phrases as knave girl to designate a boy child were common. In Middle English the word had various spellings: gerle, girle, and gurle.”

By the way, there is no such thing as a true hemaphrodite, according to the Intersex Society of North America.

That would require a person to be both fully male and fully female. At most, some people are born with — or develop at puberty — ambiguous genitalia. Other people may look female on the outside but have typical male anatomy on the inside (or vice versa), but that doesn’t mean they are of both sexes, the Society says. Indeed, it adds, one percent of all human “bodies differ from standard male or female.”

We’ll close with a one last surprise from the Morris Dictionary. The term “filibuster was originally a Dutch term and had nothing to do with government. Indeed, it originally meant ‘freebooting’ — private citizens’ engaging in warfare against a state with whom their country was at peace, usually for personal gain.

“The Dutch word vribuiter literally meant ‘freebooter or pirate.’ And its derivative filibuster was first used in this country during the 1850s to describe adventurers who were running guns to revolutionists in Cuba and other Central and South American countries.

“However, the term filibustering has become so completely identified with delaying tactics in the Senate that the word is not used for gun-running or piracy anymore.

Senator Bernie Sanders (I-Vt.) filibusters for eight hours to block a vote on an Obama tax bill in 2010.

“The first use of filibuster to describe obstruction of legislation by invoking parliamentary delays and resorting to prolonged speechmaking appeared in 1853, when one member of Congress sharply criticized the tactics of his rivals as ‘filibustering against the United States.'”

So the next time some Senator resorts to a filibuster to forestall a vote, just remind yourself that he/she is tacitly behaving like a 19th century gunrunner.