change \quote-command to display text in italics

Question

I'm using \usepackage{csquotes} and the commands blockquote and quote. I'm satisfied with the display of the blockquote but want to change the display of the quote so that the output is shown in italics.

Here's my code:

\documentclass[paper=a4, fontsize=11pt]{scrartcl} 
\usepackage{todonotes}
\usepackage[T1]{fontenc} 
\usepackage{fourier} 
\usepackage{longtable}
\usepackage{arydshln}
\usepackage[ngerman, english]{babel} 
\usepackage[utf8]{inputenc}
\usepackage{amsmath,amsfonts,amsthm} % Math packages
\usepackage{lipsum} 
\usepackage[hidelinks]{hyperref}
\usepackage{arydshln}
\usepackage{sectsty} 
\allsectionsfont{\centering \normalfont\scshape} 

\usepackage{fancyhdr} 
\pagestyle{fancyplain} 
\fancyhead{} 
\fancyfoot[L]{} % Empty left footer
\fancyfoot[C]{} % Empty center footer
\fancyfoot[R]{\thepage} % Page numbering for right footer
\renewcommand{\headrulewidth}{0pt} % Remove header underlines
\renewcommand{\footrulewidth}{0pt} % Remove footer underlines
\setlength{\headheight}{13.6pt} % Customize the height of the header


\usepackage{tikz}
\usepackage{lscape}

\usetikzlibrary{trees,shapes}
\usepackage{csquotes}
\usepackage[round]{natbib}
\bibliographystyle{plainnat}


\begin{document}
In my document I want to have two different kinds of quotes.
\begin{blockquote}
{This is a blockquote which is simply a sentence in quotation marks but otherwise part of the normal text}
\end{blockquote}
And now I have a longer quote which I want to mark as standing out, so I use the quote-environment:
\begin{quote}It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing — a somewhat unfamiliar conception for the average mind. Furthermore, the equation [...] in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa. The mass and energy were in fact equivalent, according to the formula mentioned before. This was demonstrated by Cockcroft and Walton in 1932, experimentally.
\end{quote} 

And after that quote I want to continue with the normal text.
\end{document}

My problem is that I do not get the quote to be italics. I guess it's about \renewcommand, but I cannot figure out how to incorporate something like textitin there.

Any help is highly appreciated!

---

The Einstein-quote is taken from Wikiquotes

Answer 1

I don't actually think blockquote is an environment, it's meant to be used as a macro, i.e. \blockquote{the quote}. csquotes defines a displayquote environment for this sort of thing, and redefining \mkbegdispquote to include \itshape makes it italic.

\documentclass[paper=a4, fontsize=11pt]{scrartcl} 
\usepackage{csquotes}
\renewcommand{\mkbegdispquote}[2]{\itshape}
\begin{document}
In my document I want to have two different kinds of quotes.
\blockquote{This is a blockquote which is simply a sentence in quotation marks but otherwise part of the normal text}
And now I have a longer quote which I want to mark as standing out, so I use the quote-environment:
\begin{displayquote}
It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing — a somewhat unfamiliar conception for the average mind. Furthermore, the equation [...] in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa. The mass and energy were in fact equivalent, according to the formula mentioned before. This was demonstrated by Cockcroft and Walton in 1932, experimentally.
\end{displayquote} 
And after that quote I want to continue with the normal text.
\end{document}

You can also use the \blockquote command for both quotes. It is designed such that if it a exceeds a given number of lines in length (4 by default) it is typeset as a displayed environment instead. By default the quote environment is used, but you can for example use \AtBeginEnvironment{quote}{\itshape} to set all quote environments in italics. \AtBeginEnvironment is provided by the etoolbox package, which is loaded by csquotes.

\documentclass[paper=a4, fontsize=11pt]{scrartcl} 
\usepackage{csquotes}
\AtBeginEnvironment{quote}{\itshape}
\begin{document}
In my document I want to have two different kinds of quotes.
\blockquote{This is a blockquote which is simply a sentence in quotation marks but otherwise part of the normal text}
And now I have a longer quote which I want to mark as standing out, so I use the quote-environment:
\blockquote{It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing — a somewhat unfamiliar conception for the average mind. Furthermore, the equation [...] in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa. The mass and energy were in fact equivalent, according to the formula mentioned before. This was demonstrated by Cockcroft and Walton in 1932, experimentally.} 
And after that quote I want to continue with the normal text.
\end{document}

Answer 2

The environment quote is not provided by the csquotes package, only blockquote is. With that being said, you can create a new environment itquote that applies italics to your text.

Note that the use of fancyhdr with a KOMA-script class is not recommended.

Output

Code

\documentclass[paper=a4, fontsize=11pt]{scrartcl} 
\usepackage{todonotes}
\usepackage[T1]{fontenc} 
\usepackage{fourier} 
\usepackage{longtable}
\usepackage{arydshln}
\usepackage[ngerman, english]{babel} 
\usepackage[utf8]{inputenc}
\usepackage{amsmath,amsfonts,amsthm} % Math packages
\usepackage{lipsum} 
\usepackage[hidelinks]{hyperref}
\usepackage{arydshln}
\usepackage{sectsty} 
\allsectionsfont{\centering \normalfont\scshape} 

\usepackage{tikz}
\usepackage{lscape}

\usetikzlibrary{trees,shapes}
\usepackage{csquotes}
\usepackage[round]{natbib}
\bibliographystyle{plainnat}

\newenvironment{itquote}
{\begin{quote}\itshape}
{\end{quote}}


\begin{document}
In my document I want to have two different kinds of quotes.
\blockquote{This is a blockquote which is simply a sentence in quotation marks but otherwise part of the normal text}
And now I have a longer quote which I want to mark as standing out, so I use the quote-environment:
\begin{itquote}It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing — a somewhat unfamiliar conception for the average mind. Furthermore, the equation [...] in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa. The mass and energy were in fact equivalent, according to the formula mentioned before. This was demonstrated by Cockcroft and Walton in 1932, experimentally.
\end{itquote} 

And after that quote I want to continue with the normal text.
\end{document}