# New environment. Highlight content with symbols and indentation

I'm writing my thesis and I want to highlight some part of my text which resides in a separate paragraph. I like the well-known example of

\newenvironment{king}
{\rule{1ex}{1ex}\hspace{\stretch{1}}}
{\hspace{\stretch{1}}\rule{1ex}{1ex}}


and then

\begin{king}
My humble subjects \ldots
\end{king}


But if the sentence is very long (more than one line) the result is not good looking at all, e.g.

\begin{king}
Energy is the property of matter and radiation that is manifest as a capacity to perform work.
\end{king}


I'm wondering how I can keep the margins (left and right), repeat the square every line and.. make it bold (or with a gray background).

Thanks for any help Alex PS: This is my first post so I hope it's good

-

\documentclass{article}
\usepackage{environ}
\usepackage{lipsum}

\makeatletter
\newif\ifboxended
\def\centervbox#1{\begingroup\global\setbox\@ne=\box\voidb@x
\global\boxendedfalse
\setbox\z@=\copy#1\relax\docentervbox}
\def\docentervbox{%
\setbox\z@=\vbox{\unvbox\z@
\ifcase\lastnodetype
% char node (can't remove)
\or
% hlist node
\setbox\tw@=\lastbox
\def\next{%
\global\setbox\@ne=\vbox{
\hbox to\hsize{\rule{1ex}{1ex}\hfil\box\tw@\hfil\rule{1ex}{1ex}}\unvbox\@ne}}%
\or
% vlist node
\setbox\tw@=\lastbox
\def\next{%
\global\setbox\@ne=\vbox{
\hbox to\hsize{\rule{1ex}{1ex}\hfil\box\tw@\hfil\rule{1ex}{1ex}}\unvbox\@ne}}%
\or
% rule node (can't remove)
\or
% ins node (can't remove)
\or
% mark node (can't remove)
\or
\or
% ligature node (can't happen)
\or
% disc node (can't happen)
\or
% whatsit node (can't remove)
\or
% math node (can't remove)
\or
% glue node
\skip@=\lastskip\unskip
\def\next{\global\setbox\@ne=\vbox{\vskip\skip@\unvbox\@ne}}%
\or
% kern node
\dimen@=\lastkern\unkern
\def\next{\global\setbox\@ne=\vbox{\kern\dimen@\unvbox\@ne}}%
\or
% penalty node
\count@=\lastpenalty\unpenalty
\def\next{\global\setbox\@ne=\vbox{\penalty\count@\unvbox\@ne}}%
\or
% unset node (can't happen)
\or
% math mode node (can't remove)
\else
% empty list
\def\next{\global\boxendedtrue}
\fi
\next}
\ifboxended
\def\next{\unvbox\@ne\endgroup}
\else
\let\next\docentervbox
\fi
\next}
\makeatother
\NewEnviron{king}{%
\trivlist\item\relax
\endtrivlist
}

\begin{document}

\lipsum[2]

\begin{king}
Energy is the property of matter and radiation that is manifest as a capacity to perform work.
\end{king}

\lipsum[2]

\begin{king}
My humble subjects
\end{king}

\lipsum[2]

\end{document}


-
I tried to adapt the quote code, but I found it really difficult and complicated. More than copy-paste I don't know what to do, for example to make the text of the environment bold. –  Alex Jul 31 '12 at 15:14
@Alex If you want to make all the text bold, just add \bfseries after \centering before \BODY: \BODY stands for the environment's content. –  egreg Jul 31 '12 at 16:28