Candide, ou L'optimisme, traduit de l'allemand de M. le docteur Ralph (in English, Candide, or Optimism, translated from the German of Dr. Ralph), written by Voltaire, was first published in 1759. The 1761 edition of the book included revisions made by Voltaire and was titled Candide, or Optimism, Translated from the German of Dr. Ralph. With the additions found in the Doctor's pocket when he died at Minden, in the Year of Grace 1759.

Candide is therefore ostensibly narrated by Dr. Ralph, a third-person omniscient narrator who supposedly knows everything about the stories and the characters in the book and who can travel freely through time and in and out of the character's minds. In fact, Dr. Ralph serves only as an intermediary between Voltaire and the persons who told Dr. Ralph the stories, which Voltaire presumably translated from German and put into book form.

Candide is written in a "frame narrative" structure—or a "story-within-a-story" structure—in which Dr. Ralph is telling a story about other stories that were told to him. These individual stories were told to Dr. Ralph by either a first-person or second-person narrator, and the reliability of the narration is entirely dependent on the reliability of the narrator telling the story to Dr. Ralph. Accordingly, the stories in the book might be absolutely true, absolute nonsense, or something in between.

Since Candide is a work of fiction, none of the stories are true. There is no Dr. Ralph, and, as far as we know, Voltaire made up the whole book, all by himself.

For the sake of discussion, however, in order to determine the truth of each story (or part of each story) as well as the reliability of each narrator of each story (or part of each story), it would be necessary to (1) discover the identity of the original narrator of each story (or part of each story), and (2) determine the reliability, or lack thereof, of that narrator based on the information contained in the book about that particular narrator, which information itself might or might not be reliable, depending on the reliability of the narrator who provided the information about original narrator. Second-person narrators of the original stories will be impossible to identify unless they're named in the book or unless Dr. Ralph kept notes and those notes are still available. This is problematic because there is no Dr. Ralph, so there are probably no such notes.

Such an exercise would be utterly futile, of course, and ultimately pointless. Based on the information in the book—which may or may not be reliable—most, if not all, of the characters in the book are lunatics whose reliability is questionable at best.

There's also the question of the quality and trustworthiness of the translation of Dr. Ralph's second-hand and third-hand stories from the original German into French—presumably by Voltaire, although nothing is certain—and then into English, in any of the many, many translations of Candide from French to English which have come down to us in the past 260-odd years.

It is Candide's naivety and unfailing optimism that make him such a reliable narrator. There's no lying in him, and his remarkable honesty is an expression of his generally sunny outlook on life. His very name gives us a clue as to his chief personality trait. "Candide" does not mean "candid," but rather "naive," or "innocent." That being the case, there's no reason for us to suspect that our hero is keeping anything from us.

No matter how much adversity Candide encounters on his long, eventful journey, he still remains upbeat. Whether this is the appropriate attitude to hold in the face of such an endless litany of woes is a moot point, but there can be no doubting Candide's sincerity. And so we're as certain as we can be that Candide's account of events is largely accurate.

However, Candide's innocence also means that he lacks a little something in the way of knowledge. He is astonishingly ignorant of the ways of the world, and his ignorance all too often leads him into serious trouble. This means that, although Candide reliably narrates the events as they happened to him, he is unable to provide us with a full picture of reality. For that we will need to make our own judgments, bringing to bear our own individual life experiences on the events of the story as they are—honestly and accurately—presented to us.

Candide is far too gullible to be a trustworthy narrator. He is what is called an unreliable narrator.

As with Gulliver in Swift's Gulliver's Travels, Candide is too quick to believe what he is told. For example, he buys wholeheartedly into Pangloss's flattened and absurd version of Gottfried Leibniz's philosophy that everything happens for the best in the best of all possible worlds.

It takes quite a lot of over-the-top cartoonish horror and violence for Candide to begin to think that perhaps everything is not for the best in this particular world. The comedy emerges directly from the disconnect between Candide's naive ideas and the reality the reader witnesses.

It is only after many terrible adventures and experiencing much arbitrary cruelty that Candide adopts a new philosophy, deciding that it is better to lead a life of retirement and to "cultivate one's garden" than to engage too deeply with a barbaric world.

Candide is unfailingly optimistic after every disaster that befalls him. He always thinks that "everything is for the best" and that he lives in "the best of all possible worlds." He has been taught by his teacher, Pangloss, to believe that everything is for the best, so even after he is exiled from the castle where his beloved, Cunegonde, lives and is robbed and forced to fight a war and beg for food, he says in chapter 3:

It was necessary that I should be banished from the presence of Miss Cunegonde; that I should afterwards run the gauntlet; and it is necessary I should beg my bread, till I am able to get it. All this could not have been otherwise.

Even after Candide and Pangloss witness the deadly Lisbon earthquake (a real event that happened in 1755) in chapter 5, Pangloss still says that all has happened for the best, and Candide is in agreement. Voltaire is satirizing a school of philosophy called Leibnizian optimism through the characters of Candide and his teacher, Pangloss. Candide is clearly a subjective narrator who is not to be trusted as reliable.