If anyone understood the political power of the pen, it was Herbert Block.

The editorial cartoonist, who was known for his sharp and witty political commentary, churned out more than 14,000 cartoons under the pen name of “Herblock” during his 70-year career.

Forty of Block’s most pointed drawings will be on display starting Friday at the National Portrait Gallery. Though the selections in “Herblock’s Presidents: ‘Puncturing Pomposity’” cover 11 presidencies — Franklin Roosevelt through Bill Clinton — and a broad range of issues, all capture Block’s signature style of uncanny caricatures and unfettered criticism.

His work “was terribly important because sometimes he was the only voice, not only in the city, but in the country, against things that people should have been against,” said Jean Rickard, executive director of the Herb Block Foundation and a friend and colleague of the artist for more than 40 years.

National Portrait Gallery historian Sidney Hart, the curator of the exhibit, characterized Block as “the greatest cartoonist by far in the 20th century.” Hart became a fan of Block’s work as a teenager.

Block’s cartoons always displayed a distinct, typically left-leaning, point of view.

“They’re all controversial. They’re meant to be,” Hart said. “He said, ‘You should not do cartoons in shades of gray.’”

Block worked under the belief that pieces exposing the shortcomings and hypocrisies of administrations were the most influential.

“When he dealt with the president in a negative way, those were by far the most powerful [cartoons],” Hart said.

The artist picked up his pen at a young age, drawing cartoons for his high school newspaper and interning as a cartoon artist at the Chicago Daily News during his college years. He was soon offered a job as an editorial cartoonist with the Newspaper Enterprise Association, where he narrowly escaped being fired over ideological clashes with his editors by winning his first Pulitzer Prize. He joined The Washington Post in 1946 after a three-year stint in the Army and served as the Post’s lead editorial cartoonist for 56 years before his death in 2001.

Hart said Block was known for immersing himself in news and politics, going to the offices of the Post and reading through articles from the previous day until he found a topic for his next cartoon. Hart said he and others completing research for the exhibit could often pinpoint which story had inspired the drawing at hand.

“I think a lot of it is by osmosis and it is a central thing that he dedicates his life to,” Hart said of Block’s intimate understanding of the American political system.

Though he was unsympathetic to conservative policies and presidents, pointing out the shortfalls of Democrats did not faze Block. Pieces on display take jabs at everything from Ronald Reagan’s strong communication and speaking skills, playing off a “Through the Looking Glass” motif and accusing Reagan of creating a make-believe world with his rhetoric, to Lyndon Johnson’s decision to divert funds from fighting poverty to the war in Vietnam.

The most influential and powerful series of cartoons Block drew were the pieces after Watergate, Rickard said.

For the most part, Block enjoyed complete editorial freedom at the Post, Hart said, but the post-Watergate pieces were so critical that Post editors were hesitant to publish them.

As with many of his subjects, the disdain was mutual. Nixon, whom Hart described as “the first in a line of presidents Block didn’t want to meet,” was so put off by Block’s stubble-chinned renderings of him that he reportedly shaved two times a day to keep up a clean-cut appearance. Both Nixon and Dwight Eisenhower also canceled subscriptions to the Post in response to unflattering drawings.

“Most of the guys who become president, they have huge egos and they don’t like those egos being stepped on,” Hart said.

The cartoons will be on display in a room adjacent to the museum’s gallery of presidential portraits and Hart said the timing, which comes just one year shy of what would be have been Block’s 100th birthday and coincides with the 2008 elections, will serve as a lighthearted lesson of what’s to come for presidential hopefuls.

“We thought during an election year it was a good exhibit to have, warning those that want to be president,” he said.

“Puncturing Pomposity” will be on display at the National Portrait Gallery through Nov. 30. The museum is open 11:30 a.m. to 7 p.m. daily and is located at Eighth and F streets Northwest.