In Chapter 18, Dorothy is distraught to learn that the Winged Monkeys cannot take her to Kansas and that by asking them to do so, she has wasted one of her three allotted wishes of them. The Scarecrow immediately begins thinking about what to do next, and Baum uses absurd imagery that highlights the situational irony of the Scarecrow's belief that the Wizard has made his brain more functional:
‘I have wasted the charm of the Golden Cap to no purpose,’ she said, ‘for the Winged Monkeys cannot help me.’
‘It is certainly too bad!’ said the tender-hearted Woodman.
The Scarecrow was thinking again, and his head bulged out so horribly that Dorothy feared it would burst.
The image of the Scarecrow's grotesquely bulging head is "horrible" to Dorothy, but it is laughable to the reader. The Scarecrow spent the first two thirds of the book convinced that his head was empty. Despite this belief, he was the main strategist among Dorothy's friends all along. For example, it was the Scarecrow who thought of the plan to enlist the field mice to help save the Cowardly Lion from the field of poppies. Now that Oz has filled his head with bran (not even real brains), the Scarecrow is still strategizing the same as ever. The only difference is that now, his head keeps bulging out dangerously and comically. It is ironic that the Scarecrow thinks he is better off now when, in fact, he seems to have more in his head than can fit. He would really have been better off if he had started believing in himself instead of insisting that he needed the Wizard to overstuff his head.
