Configuring the looks of memoir's \paragraph

Question

I need a lower heading level than subsubsection and hence I am turning towards \paragraph. I am happy with not having it numbered but I do want it to stand on a line of it's own and be italic. I have tried the following:

\documentclass{memoir}
\usepackage{lipsum}
\begin{document}

\setparaheadstyle{\itshape}
\let\origparagraph\paragraph
\renewcommand*{\paragraph}{%
\origparagraph{#1} \\ 
}

\paragraph{Lorem ipsum}
\lipsum[1-2]

\end{document}

which sadly gives me:

! Illegal parameter number in definition of \paragraph.
<to be read again> 
                   1
l.9 }

So clearly I can't renew the \paragraph command quite in that way. How should I do it?

Answer 1

\setparaheadstyle{\normalsize\itshape}
\setafterparaskip{1ex}

Choose the value that suits you; if you want no vertical space use 1sp instead of 0pt as a positive value (even the smallest one) forces a line break.

You probably already know that to number paragraphs you have to say

\setsecnumdepth{paragraph}

which corresponds to the traditional LaTeX

\setcounter{secnumdepth}{4}

If you don't want an indented paragraph just after the title, say also

\setbeforeparaskip{-\beforeparaskip}

which suppresses the indentation, keeping the same vertical spacing before the title.

Answer 2

For what is worth, you must indicate that you're expecting a value, so you have to write \renewcommand*\paragraph[1]{re-definition} this [1] means that you're expecting a value, which you call with #1.

See the wikibook on LaTeX for more details.