Pairing Items for Display in Two Columns

Question

I have am putting together a list of enumerated items in which I would like to pair consecutive items: 1,2 ; 3,4; 5,6; etc. so that the odd numbered item appears on the left hand side of a two-column display with the even numbered item shown immediately to its right.

Consider

\documentclass[12pt]{book}
\usepackage{multicol}

\begin{document}
\centering{BOOK I}
\begin{multicols}{2}
\begin{enumerate}
\item Et quid curse nobis de generibus et speciebus.

\item Quanto aliquis magis sibi unitus et interius simplificatus fuerit.

\item Ejus conversatio non cum popularibus.

\item Qui bene in pace est.

\item Probabile.

\item Aperit sensum puris mentibus,
\end{enumerate}
\end{multicols}
\end{document}

which produces (unfortunately):

I was hoping that a two-column multicol environment would alternate between the left and right hand columns for each consecutive entry, but this is not the case.

QUESTION: (i) How may I produce a two-column display so that the odd numbered items appear on the left and the even numbered items on the right; and (2) have the items shown in such a way that it is clear that the second item is paired with the first, the fourth with the second, and so on? (This would be accomplished if, say, the third item was displayed immediately lower than the first two; the fifth immediately lower than the third and fourth.)

In the document I am working on, I have, perhaps, thirty or so such items and the pairings will need to break across pages.

Answer 1

\documentclass{article}
\usepackage{multienum,lipsum}
\begin{document}
\begin{multienumerate}
\mitemxx{\lipsum[1][1]}{\lipsum[1][2-3]}
\mitemxx{\lipsum[1][4]}{\lipsum[1][5]}
\mitemxx{\lipsum[1][6]}{\lipsum[1][7-12]}
\end{multienumerate}
\end{document}