All writers who understand human nature are clever.
No one is a true poet unless he can stir the hearts of men.
Shakespeare wrote Hamlet.
No writer who does not understand human nature can stir the hearts of men.
None but a true poet could have written Hamlet.
Shakespeare was clever.

The following sorites are taken from Lewis Carroll’s Symbolic Logic. All are valid. Rewrite each sorites in standard form, using letters to represent the terms and reducing the number of terms whenever necessary. Then use Venn diagrams or the rules method to prove each one valid.