How do I create this text delimiter?

Question

I want to create a delimiter between two regular paragraphs of text as in the end of page 6 of this pdf.

One way out could be the Vmatrix environment but then I dont know how to make the right delimiter disappear. Quick googling suggested only the usual way of using \right. to make a delimiter disappear but that wont work here.

How do I do this?

Answer 1

\documentclass{article}
\usepackage{amsmath,tabularx}
\usepackage{lipsum}
\begin{document}

\begin{tabularx}{\linewidth}{@{}|| X @{}}
\lipsum*[1]
\end{tabularx}

\end{document}

Answer 2

I used the framed package to define a dleftbar environment to enclose the contents using a double vertical rule; then, this environment was used in conjunction with the amsmath package to define some theorem-like structures (admitting page breaks):

\documentclass{book}
\usepackage{framed}
\usepackage{amsmath}
\usepackage{lipsum}

\newenvironment{dleftbar}{%
  \def\FrameCommand{\vrule width 0.4pt\hspace{1.7pt}\vrule width 0.4pt \hspace{6pt}}%
  \MakeFramed {\advance\hsize-\width \FrameRestore}}%
 {\endMakeFramed}

\newtheorem{theorem}{Theorem}[chapter]
\newtheorem{proposition}[theorem]{Proposition}

\newenvironment{prop}
  {\begin{proposition}\begin{dleftbar}}
  {\end{dleftbar}\end{proposition}}
\newenvironment{theo}
  {\begin{theorem}\begin{dleftbar}}
  {\end{dleftbar}\end{theorem}}

\begin{document}

\chapter{Test Chapter}
\lipsum[2]
\begin{theo}
\lipsum[2]
\end{theo}
\begin{prop}
\lipsum[2]
\end{prop}

\end{document}