[jQuery] How to select an element based on visibility

[jQuery] How to select an element based on visibility


Hi,I cannot get my finger behind this one:
I have this HTML:
<p class="firstLine">This is the first line of the first paragraph

And here is some more text. Bladibladibla


<p class="firstLine">This is the first line of the secons paragraph</
p>

And here is some more text. Bladibladibla


<p class="firstLine">This is the first line of the third paragraph

And here is some more text. Bladibladibla


when I click a

class firstLine, I want the paragraph immediately
_below_ it to disappear if it is visible. If it is invisible, I want
it to show again.
This
$(document).ready(function(){
    $(".firstLine").click(function(){
        var el = $(this).next();
        $("el:hidden").click.slideDown("slow");
        $("el:visible").click.slideup("slow");
    });
});
doesn't work.
How can I do this?
Thanks