# Recover style of \section modified by titlesec

After the \section style is modified by the titlesec package, I want to return to the original style by \let and \renewcommand, but fails. Why and how to achieve this?

MWE:

\documentclass{article}
\usepackage{titlesec,xcolor}

\begin{document}
\section{Original Section Style}
\let\oldsection\section %store the original macro \section
\oldsection{Original Section Style stored}
\titleformat{\section}{\huge\color{red}}{\Roman{section}}{1em}{}
\section{New Section Style}
\let\section\oldsection % recovery of \section
\renewcommand{\thesection}{\arabic{section}}% I tried by another way
\section{I want to restore the original section style, but fails}
\end{document}


• Different section styles may confuse readers however, as it breaks the coporate design somehow – user31729 Feb 16 '19 at 11:06

In section 9.2 of the titlesec manual, you find that the default style for \section is

\titleformat{\section}{\normalfont\Large\bfseries}{\thesection}{1em}{}


Thus you can go back and forward:

\documentclass{article}
\usepackage{titlesec,xcolor}

\newcommand{\originalsections}{%
\titleformat{\section}{\normalfont\Large\bfseries}{\thesection}{1em}{}%
}
\newcommand{\modifiedsections}{%
\titleformat{\section}{\huge\color{red}}{\Roman{section}}{1em}{}%
}

\originalsections

\begin{document}

\section{Original Section Style A}
\section{Original Section Style B}

\modifiedsections

\section{New Section Style A}
\section{New Section Style B}

\originalsections

\section{Original Section Style C}

\end{document}


The old definition of \section etc. must be captured by a \let statement

before

titlesec changes \section etc, i.e.

\let\oldsection\section
\usepackage{titlesec}


Here is the modified code:

\documentclass{article}

\let\oldsection\section %store the original macro \section

\usepackage{titlesec}
\usepackage{xcolor}

\begin{document}

\section{Original Section Style}
\oldsection{Original Section Style stored}
\titleformat{\section}{\huge\color{red}}{\Roman{section}}{1em}{}
\section{New Section Style}
\let\section\oldsection % recovery of \section
\renewcommand{\thesection}{\arabic{section}}% I tried by another way
\section{I want to restore the original section style, but fails}
\end{document}