I wish to have a "Introduction" section that is not numbered, with subparts within it. I wish the subsections of that section not to be numbered, yet the whole thing to appear in the table of contents.
If I use
\section*{Introduction}
\addcontentsline{toc}{section}{Introduction}
\subsection{First part of intro}
...
\subsection{Second part of intro}
...then the \subsection commands will (in the numbering scheme I use) generate numbering such as "0.1 First part of intro" both in-text and in the TOC.
The following generates what I want:
\section*{Introduction}
\addcontentsline{toc}{section}{Introduction}
\subsection*{First part of intro}
\addcontentsline{toc}{subsection}{First part of intro}
...
\subsection*{Second part of intro}
\addcontentsline{toc}{subsection}{Second part of intro}
Is there a way to automagically do this? My problem is that I have to type the \addcontentsline everywhere, when I would like to have something where \section* triggers a switch to "non-numbered mode" where each \subsection command is expanded to the pair of \subsection*;\addcontentsline commands or something similar (and the next \section switches back to "numbered mode").
EDIT: disabling numbering of subsections for the whole document is not desired.

\frontmatterusually turns of the numbers of\chapteronly. Withbookthe section numbers even still have the chapter prefix, e.g.,0.. Other classes may behave different, e.g.,scrbookomits the chapter number prefix forsection,subsectionetc. andfigureandtable. – Schweinebacke Feb 07 '17 at 10:05