Quote Environment à la Strunk’s ‘The Elements of Style’

Question

How can I have a an environment similar to Strunk's The Elements of Style:

Answer 1

Here's the environment, actually three:

\documentclass[twocolumn]{article}
\usepackage{mathpazo}
\usepackage{xcolor}

\newsavebox{\strunkbox}
\newenvironment{strunk}
  {\begin{lrbox}{\strunkbox}
   \begin{minipage}{.8\columnwidth}}
  {\end{minipage}\end{lrbox}\begin{center}
   \setlength{\fboxrule}{1pt}
   \leavevmode\color{red}
   \fbox{\usebox{\strunkbox}}
   \end{center}}
\newenvironment{swrong}
  {\addvspace{2ex}\begin{minipage}[t]{.45\textwidth}\footnotesize}
  {\end{minipage}\ignorespacesafterend}
\newenvironment{sright}
  {\hfill\begin{minipage}[t]{.45\textwidth}\footnotesize}
  {\end{minipage}\par}


\begin{document}
Words that intervene between subject and verb do not affect the number of the verb.
\begin{strunk}
\begin{swrong}
The bittersweet flavor of youth---its trials, its joys, 
its youth---are not soon forgotten
\end{swrong}
\begin{sright}
The bittersweet flavor of youth---its trials, its joys,
its youth---is not soon forgotten
\end{sright}
\end{strunk}
A common blunder is the use of a singular verb form in a relative clause 
following ``one of\ldots'' or a similar expression when the relative is the 
subject.
\begin{strunk}
\begin{swrong}
One of the ablest scientists who has attacked this problem
\end{swrong}
\begin{sright}
One of the ablest scientists who have attacked this problem
\end{sright}

\begin{swrong}
One of those people who is never ready on time
\end{swrong}
\begin{sright}
One of those people who are never ready on time
\end{sright}
\end{strunk}
Use a singular verb form after \emph{each, either, everyone, everybody,
 neither, nobody, someone}.
\end{document}

Don't leave blank lines between \end{swrong} and \begin{sright}.

Answer 2

Rather than as an environment, I create \strunk{}{} for the task. It will not break across page breaks. I have limited \textwidth here, instead of using columns. The \strunk macro will occupy 85% of \textwidth, plus the red border.

\documentclass{article}
\usepackage{xcolor}
\parskip 1ex
\textwidth 3in
\parindent 0in
\fboxrule 3pt
\newcommand\strunk[2]{%
\par{\centering
\color{red}{\fbox{\color{black}\scriptsize
\begin{minipage}[t]{.4\textwidth}
\parskip 1em
\raggedright#1
\end{minipage}
\hspace{.05\textwidth}
\begin{minipage}[t]{.4\textwidth}
\parskip 1em
\raggedright#2
\end{minipage}
}}
\par}
}
\begin{document}
Words that intervene between subject and verb do not affect the number of the verb.
\strunk
{The bittersweet flavor of youth---its trials, its joys, its youth---are not soon 
forgotten}
{The bittersweet flavor of youth---its trials, its joys, its youth---is not soon 
forgotten}
A common blunder is the use of a singular verb form in a relative clause 
following ``one of\ldots'' or a similar expression when the relative is the 
subject.
\strunk
{One of the ablest scientists who has attacked this problem

One of those people who is never ready on time}
{One of the ablest scientists who have attacked this problem

One of those people who are never ready on time}
Use a singular verb form after \textit{each, either, everyone, everybody,
 neither, nobody, someone}.
\end{document}

Answer 3

Another solution for those (like me) who doesn't manage low level commands like egreg and Steven. It uses tcolorbox and its possibility of arranging two texts side by side. strunk is an environment instead of a command but I hope it doesn't matter.

\documentclass[twocolumn]{article}
\usepackage[most]{tcolorbox}
\usepackage{mathpazo}

\newtcolorbox{strunk}{notitle, colback=white, colframe=red, width=.9\linewidth,
              arc=0pt, outer arc=0pt, 
              sidebyside, lower separated=false, sidebyside align=top, sidebyside gap=4mm,
              before={\par\smallskip\pagebreak[0]\parindent=0pt\centering},
              after={\par\smallskip},
              fontupper=\small, fontlower=\small,
              boxsep=0mm,
              left=2mm, right=2mm, top=2mm, bottom=2mm,
              }

\begin{document}
Words that intervene between subject and verb do not affect the number of the verb.
%
\begin{strunk}
{The bittersweet flavor of youth---its trials, its joys, its youth---are not soon 
forgotten}\tcblower
{The bittersweet flavor of youth---its trials, its joys, its youth---is not soon 
forgotten}
\end{strunk}

A common blunder is the use of a singular verb form in a relative clause 
following ``one of\ldots'' or a similar expression when the relative is the 
subject.


\begin{strunk}
{One of the ablest scientists who has attacked this problem\\

One of those people who is never ready on time}\tcblower
{One of the ablest scientists who have attacked this problem\\

One of those people who are never ready on time}
 \end{strunk}

  Use a singular verb form after \textit{each, either, everyone, everybody,
 neither, nobody, someone}.

\end{document}

Answer 4

Here's another tcolorbox alternative in two variants.

The first one builds upon the answer of @Ignasi. I polished it at some spots, especially to answer the indention questions which came up in the comments:

\documentclass[twocolumn]{article}
\usepackage[skins]{tcolorbox}
\usepackage{mathpazo}

\newtcolorbox{strunk}{colback=white,colframe=red,
  width=.9\linewidth,
  size=fbox,boxrule=2pt,
  sharp corners,lower separated=false,
  sidebyside,sidebyside align=top,
  sidebyside gap=4mm,
  before={\begin{center}},
  after={\end{center}},
  fontupper=\small, fontlower=\small,
}

\begin{document}
Words that intervene between subject and verb do not affect the number of the verb.
%
\begin{strunk}
  The bittersweet flavor of youth---its trials, its joys, its youth---are not soon
  forgotten.
\tcblower
  The bittersweet flavor of youth---its trials, its joys, its youth---is not soon
  forgotten.
\end{strunk}
A common blunder is the use of a singular verb form in a relative clause
following ``one of\ldots'' or a similar expression when the relative is the
subject.
\begin{strunk}
  One of the ablest scientists who has attacked this problem\bigskip

  One of those people who is never ready on time
\tcblower
  One of the ablest scientists who have attacked this problem\bigskip

  One of those people who are never ready on time
\end{strunk}
Use a singular verb form after \textit{each, either, everyone, everybody,
neither, nobody, someone}.

\end{document}

Since the OP mentioned that the red borders are not really intended to appear in the document, here is a second variant without borders:

\documentclass[twocolumn]{article}
\usepackage[skins]{tcolorbox}
\usepackage{mathpazo}

\newtcolorbox{strunk}{blanker,
  width=.9\linewidth,
  sharp corners,lower separated=false,
  sidebyside,sidebyside align=top,
  sidebyside gap=4mm,
  before={\begin{center}},
  after={\end{center}},
  fontupper=\small, fontlower=\small,
}

\begin{document}
Words that intervene between subject and verb do not affect the number of the verb.
%
\begin{strunk}
  The bittersweet flavor of youth---its trials, its joys, its youth---are not soon
  forgotten.
\tcblower
  The bittersweet flavor of youth---its trials, its joys, its youth---is not soon
  forgotten.
\end{strunk}
A common blunder is the use of a singular verb form in a relative clause
following ``one of\ldots'' or a similar expression when the relative is the
subject.
\begin{strunk}
  One of the ablest scientists who has attacked this problem
\tcblower
  One of the ablest scientists who have attacked this problem
\end{strunk}
\begin{strunk}
  One of those people who is never ready on time
\tcblower
  One of those people who are never ready on time
\end{strunk}
Use a singular verb form after \textit{each, either, everyone, everybody,
neither, nobody, someone}.

\end{document}