SO CAUSTIC are a number of the entries in the Dictionary of National Biography that in England it is said that the DNB has added a new terror to death. It might as easily be said that the foreboding prospect of confronting on the White House breakfast tray the morning's Washington Post carrying Herblock's latest cartoon has added a new misery to the burden of the modern presidency.

Herblock Through the Looking Glass, the ninth collection of his pictures with accompanying text that Herbert Block has published, covers the period since 1980. Not all of the book has a political focus -- there are some mordant assaults on drunken driving -- but almost everything takes places in Reaganland, and it is the present incumbent who is, overwhelmingly, the most conspicuous target. Mondale's speechwriters will mine the test for examples of Reagan's more egregious gaffes and historians will turn to it for a catalogue of the president's shortcomings. Inevitably, however, it is not the text, lively and often amusing though it is, that rivets our attention, but the cartoons.

The portrait of Ronald Reagan that emerges from these pages is devastating. A blunderer who barges from one disaster to the next, the president is forever blaming others for his follies. In one cartoon, he stands holding a smoking gun over the bullet- ridden corpse of "A Responsible Budget Policy" while claiming "The butler did it," as he points toward Congress, attired in a servant's livery. In another, Reagan wheels a baby carriage containing two Reagan-faced infants, ''Reagan All-Time-Record Deficits" and "Reagan Depression," as he tells a bemused passer-by, "They were left under a cabbage by previous presidents." In yet another drawing, the White House desk is revealed to be bearing the plaque, "The Buck Passes Here."

A man incapable of owning up to error, Reagan, in Herblock's panorama, presides blithely over an administration that is grossly unjust. "I'm in the same age bracket as you," declares the president (annual income more than $500,000, including nearly $18,000 in governor's pension) as he stares down at an elderly man (Social Security minimum benefits, $2,044 yearly). In a hard-hitting, and not wholly fair, sketch, Reagan and Ed Meese, as they whiz past a poor wretch huddled on a Washington sidewalk in their chauffeur- driven limousine, remark, "Strange how some choose to live like that instead of choosing to be rich like us." And in the Christmas season of 1983, the star of Bethlehem shines brightly while the fortress-like "Reagan-Meese Inn," its doors and windows barred, displays a sign, "No Vacancy."

Above all, Reagan is portrayed as a media creature who fosters a politics of unreality as he transports the nation in his "Magic Backward Time Machine" on the "Nostalgia Special" to "Coolidge Country & McKinleyville." One cartoon captures him on a bitter wintry day against the fake backdrop of hokey sunlit scene while in another the president instructs a hard-hatted ''Reagan wrecker" on a street in which nothing has been left standing of the buildings of regulatory agencies save their false fronts, "Leave the facades -- it'll be just like Hollywood."

THE MOST GIFTED of the political cartoonists have an effect on the way we perceive history that few writers can match. No amount of revisionist scholarship on the nefarious Tweed Ring has much of a chance of altering the impression left by Thomas Nast's caricatures. Our understanding of the Appeasement chimera will always reflect the imagery of David Low. And historians will attempt in vain to persuade us that we should have a more charitable view of Joe McCarthy, for Herblock has shown us who he was: a skulking, roundshouldered villain, disfigured by 5 o'clock shadow, in pursuit of innocent prey. It was, indeed, Block who added the word "McCarthyism" to the lexicon. By coincidence, his new book appears at the same time as a volume by William Bragg Ewald Jr. seeking to establish that it was Eisenhower who brought McCarthy down. But it is improbable that the best of Ewald's efforts will overcome a single Herblock sketch -- a glowering, confident McCarthy, meat cleaver in hand, looking contemptuously at a feckless Eisenhower saying "Have a care, sir," as he draws from his scabbard a feeble feather.

In the end, no characterization of Ronald Reagan may have as lasting an effect on his place in history as the impression Herblock has given us of him and of our contemporary political culture. If all of the other cartoons in this book missed the mark -- and they surely do not -- a single frame would be enough to establish Herblock's mastery. For the cartoon that adorns the jacket and gives the book its name is destined to illustrate histories of our time for years to come. In this arresting tableau, a complacent Reagan is sealed off from reality by a television screen that projects his sappy grim, while Alice, dressed in the costume made familiar by Sir John Tenniel, seeks to penetrate this looking glass illusion. No words that will be written about America in the 1980s are ever likely to capture so indelibly the fantasy universe in which we now dwell.