Certain

I'm certain of a lot of things
But certain is as certain does;
Reason certainty oft brings
Of what one did or what one was
But sometimes faith can certain make
What reason wishes left behind
Or lies can of a sudden take
A false new form, and thus designed
Implant a certain notion in
A mind prepared to be deceived
So even certain things begin
To be examined ere believed
But high above such certainty
Is my belief that you love me.