Break the following monoalphabetic substitution cipher. The plaintext, consisting of letters only, is an excerpt from a poem by Lewis Carroll.
mvyy bek mnyx n yvjjyr snijrh invq n muvjvdt je n idnvy jurhri n fehfevir pyeir oruvdq ki ndq uri jhrnqvdt ed zb jnvy Irr uem rntrhyb jur yeoijrhi ndq jur jkhjyri nyy nqlndpr Jurb nhr mnvjvdt ed jur iuvdtyr mvyy bek pezr ndq wevd jur qndpr mvyy bek, medj bek, mvyy bek, medj bek, mvyy bek wevd jur qndpr mvyy bek, medj bek, mvyy bek, medj bek, medj bek wevd jur qndpr