Zadig has been called a philosophical novella—and for good reason. Strung throughout the episodic story are a series of parables that teach lessons about ethics and morality. In most cases, it is the story’s protagonist, Zadig, who is teaching. Zadig teaches verbally, often through parables, allegories, and analogies to show other people a different way of thinking about things. He does so in a poetic manner, using allegorical examples and subjects. And at the same time, Zadig employs a keen intelligence to discern the truth, using what later will be known as the scientific method to see and reveal what other people cannot see.

Zadig is fined and tried early in the novella for knowing something by his judgment that he has not actually seen with his own eyes. Zadig applies his brilliant mind to prove the existence of a horse and dog at a scene, using the physical evidence they have left behind to infer their earlier presence.

As I was walking down the Lane by the Thicket-side, I took particular Notice of the Prints made upon the Sand by a Horse’s Shoes; and found that their Distances were in exact Proportion; from that Observation, I concluded the Palfrey gallop’d well. In the next Place, the Dust of some Trees in a narrow Lane, which was but seven Foot broad, was here and there swept off, both on the Right and on the Left, about three Feet and six Inches from the Middle of the Road. For which Reason I pronounc’d the Tail of the Palfrey to be three Foot and a half long, with which he had whisk’d off the Dust on both Sides as he ran along.

Many later writers, including Sir Arthur Conan Doyle and Edgar Allan Poe, point to Voltaire’s Zadig as an inspiration and influence in the development of their own literary detectives.

When burdened by the weight of extra supplies taken from the camels, Zadig tells his master about the simple physical law of gravity. (This was a physical law that the French were slow to accept, for which Voltaire often criticized the French.)

Zadig took the Liberty to explain the Reason thereof; and convinc’d him of the Laws of the Equilibrium. The Merchant was a little startled at his philosophical Discourse, and look’d upon him with a more favourable Eye than at first.

When Zadig visits the languishing, sick Prince Ogul, the prince is having his servants look for a basilisk to cure him. Zadig tricks the prince into instead practicing daily exercise, staying sober, and using a medicine bag. This cures the prince, who continues to change his lifestyle.

Zadig teaches his Egyptian master, Setoc, how to recover a debt without having any proof of the indebtedness. The money has been counted out to the man on a large stone, and he tricks the man into admitting he knows where the stone is.

Setoc loves the stars in the sky because they are so brilliant and so far away. Zadig lights a number of candles in a room and sits and adores them while Setoc is there, ignoring Setoc. Setoc understands from this that it is the maker of the stars he should adore, not the stars themselves, a critique Voltaire is making toward the idolatrous adoration of images by Christians.

In Setoc’s land, there is an ancient practice of the burning of widows on their husband’s funeral pyres—the rite still exists merely because it is ancient. Zadig argues that this is ruinous for the women and for the state and convinces Setoc and a court of judges to amend the...