Mark Twain once observed that no one would try to play a fiddle in public without some prior instruction in the instrument, but no one had such hesitation when it came to writing.

Clearly, many candidates these days think you can run for president without any political experience or with precious little. The unqualified and the marginally equipped seem to believe they are uniquely gifted to be president of the United States.

At the moment a large school of Democrats feel that because they empathize with the working poor, the struggling middle class and are appalled by the excesses of the plutocrats, they can, when elected, put it all right. They confuse empathy with policy and achievability.

Then there are those who subscribe to the belief in business as the incubator of all skills. These are the people who believe — and they could well line up for former Starbucks CEO Howard Shultz — that if you can run a business, you can get a handle on Washington. It is a myth that just won’t die. If one can make a lot of money, it proves just one thing: One has made a lot of money. Running based on commercial success and Washington failure doesn’t work. The two worlds are not subject to the same laws of nature, as it were.

In business, you can walk away from failure; in politics, it follows you. If a franchise deal fails in business, you abandon it. You can’t abandon Russia or China because you can’t get a deal. And you can’t abandon the poor because you think you can’t afford them.

Politics is, above all, learned, and it is learned in political places — school boards, community associations, unions and state legislatures. Anywhere where offices are elective.

If you want to succeed in reshaping Washington, the first thing to do is to understand it and respect it. Yes, respect it.

We are so inured to people running against Washington that we forget that it is the product of all the others who ran against it. Washington, like all complex systems, is the sum of its parts, from the lobbyists to the agencies, and the laws which Congress has passed.

Washington is a seething, dynamic system, not too complex to be reformed but way too complex to be a candidate for simple solutions. Look at the supreme political amateur Donald Trump and see how his plan to upend Washington and “drain the swamp” has fared. In engineering and science, if you want to change something, first understand it — know its parts and their functions before you start.

Rex Tillerson, the former CEO of ExxonMobil, failed to reform the State Department because he didn’t feel he needed to understand it. He failed in his own right, even without the difficulties Trump piled on him.

If politics is war by another means, then don’t show your hand. You don’t tell the enemy where you’ll dig in or what secret weapon you’ll bring to bear. To declare the rate of tax you favor (70 percent for the rich), how you are going to implement a national healthcare system (extend Medicare) and who you’ll not  listen to (lobbyists are a great source of information), and what limits you are going to put on yourself (to draw attention to your rectitude) is neither the way to get elected nor to do the peoples’ business. Caring isn’t a plan.

Many successful presidents, from Washington to Clinton, have been bad businessmen. The best qualification for the office isn’t how well you’ve done at something else, but to have run something big and political like a charity, an advocacy group, a school, a city or a state. That way you learn the art of give a little, take a lot. Those who haven’t had this administrative experience need to study it over and over.

As Lloyd George, the British prime minister during World War I, wrote, “There is no greater mistake than to try to leap an abyss in two jumps.” Every day, I read someone is setting out to prove him wrong and run for president without regard to the geography of the politics.