<!-- generated: provider=openrouter model=arcee-ai/trinity-large-preview:free date=2026-02-19 source=book-1-chapter-04 -->

# Double Coincidence of Wants

## Definition

The requirement in barter systems that each party to an exchange must simultaneously possess exactly what the other party desires, creating a significant barrier to trade when such matching preferences cannot be found.

## Source Chapter

Book I, Chapter 4

## Context

Smith identifies this as the primary limitation of barter systems, where a butcher with meat cannot exchange with a brewer who has beer if neither desires the other's product, demonstrating why money becomes necessary for efficient commercial exchange.

## Economic Domain

Exchange

---
