Display entries if Field Date is past Now
You can combine a for and if statement in twig, so you don't necessarily need to use search.  

Something like this might get you a bit closer:

{% for entry in craft.entries.section('event') if entry.postDate &lt; now %}
{# output your event here #}
{% endfor %}


It'll just output what meets the criteria if your if statement. The bonus is it doesn't mess with your loop variables either, so things like loop.index work out as you'd expect (or at least they have for me so far). 

EDIT: Here's an alternate way of doing it, which neatens up the query and adds ordering... 

{% set events = craft.entries({
    section:  'event',
    startDate:  '&lt; ' ~ now,
    order: 'postDate desc'
}).find() %}

{% for event in events %}
...
{% endfor %}