produces a smaller increase in subjective value than the previous gain of an equal unit. The marginal utility, or the change in subjective value above the existing level, diminishes as gains increase.

As the rate of commodity acquisition increases, the marginal utility decreases. If commodity consumption continues to rise, the marginal utility will eventually reach zero, and the total utility will be at its maximum. Beyond that point, any further increase in commodity consumption leads to negative marginal utility, which represents dissatisfaction.