to collapse a pageblocksection by default

http://help.salesforce.com/apex/HTViewSolution?id=000181821&language=en_US

<apex:page >
<apex:pageBlock id="block1">
    <apex:pageBlockSection id="section1" columns="2" collapsible="true" title="Title">
        Example Area
    </apex:pageBlockSection>
    
<script> twistSection(document.getElementById('{!$Component.block1.section1}').getElementsByTagName('img')[0]) </script>
</apex:pageBlock>
</apex:page>