My first two is the name for a circle's fundamental ratio, my last two are the symbol for an element, used to make signs stand out at night. Together, I'm a synonym for yearn.

I give and take A fine line between faith and recklessness You stand more to lose A zero sum game I am

Add a letter to find boats here Remove the last to end up irrational Remove the first two and it's still irrational

How many do you see can you count them all I dare you to try it would take you a lifetime if you dared. Think of the night sky and all the stars you see how many of me do you see

I am taken before I am given, I vanish when held, I return only when lost, And I’m never the same twice.