Notice that the convexity implies that at a bundle like a′′, which contains rather a lot of wine and not much bread, the consumer would be willing to give up a considerable amount of wine in exchange for just a little more bread. (The slope of the indifference curve is quite steep at that point.) However, at a point like a′, which contains considerably more bread but less wine than a′′, the consumer is not ready to sacrifice nearly as much wine to obtain a little more bread.