To fight IT, Meg and Calvin recall the same creative geniuses who Mrs. Whatsit initially told them had dedicated their lives to waging war with the Dark Thing. That is why Calvin quotes Shakespeare and Meg recites Jefferson's Declaration of Independence to resist the rhythmic of IT's pulsing power. Meg chose the Declaration of Independence because this document protests the principles of conformity and uniformity characterised by monarchy or, here, life on Camazotz. On the planet Camazotz, inhabitants do not have individual rights because they are all exactly the same. No one has the freedom of self-determination or the inalienable right to the pursuit of happiness because all their pursuits are guided by a cold, disembodied brain.
When the Declaration of Independence fails to have the desired effect, Meg starts reciting the irrational square roots. She cannot recite the rational roots of perfect squares such as 1, 4, and 16, because these will easily lapse into IT's evil rhythm. Only the irrational roots, with their long, awkward, non-repeating decimal values, stand a chance against IT. The choice of irrational square roots is significant in resisting IT. Meg fights the tyranny of a rational brain devoid of the irrational qualities -- the passions, emotions, and foibles -- that make us human. By representing IT with a disembodied brain, L'Engle comments on the dangers of intellect without emotion. Such pure rationality stifles individuality. Without emotions, people are mechanical, robot-like creatures identical to one another. We can think creatively and develop as unique individuals only when we can feel love and pain. Trying to fight IT with his exceptional intelligence, Charles fails to withstand the evil force, his intellect alone is not sufficient. Charles's downfall is due to his failure to follow the advice of the Mrs. W's. Mrs. Whatsit cautioned him to be beware of pride and arrogance, but Charles thought that he could resist IT single-handedly. Mrs. Who warned him to remember that he does not know everything, but Charles nonetheless engaged with the Man with the Red Eyes when he lauded his neuropsychological complexity. Mrs. Which advised all the children to stay together at all times, but Charles insisted on going off with the Man in the CENTRAL Central Intelligence Building. Charles's defeat demonstrates that intelligence and intellect alone cannot resist the tyranny of uniformity.