What does Simon mean when he says, "maybe [the beast] is only us" (Page 97)?

As the boys argue and fret about an external beast, it is only Simon that has the insight to claim that the only "beast" on the island lies in their own hearts. It is only humanity that holds evil rather than any outside force imposing it.

Every individual has an innate evil and this is what Simon was referring when he used the term 'beast is us'. He views our anger, fear, envy, and all other negative attitude to be our worst enemy rather than the external forces we used to fear.

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