What Means To Think? Poem by Francis Poole

I'm not sure I even understand
what it means 'to think'
To be thinking of something
or someone
To have a thought
To lose a thought
To not be able to think
To wishful think about something
Is a wish a thought?
Is a memory a though?
Is a feeling like a thought?
Would a penny buy your thoughts?
Are they even worth a penny?
Does the brain create a thought?
Does half a brain give half a thought?
Do you think when you are asleep?
Is a dream a thought?
Does everything originate in a thought?
Can a fish have a thought?
Can a thought fill the eyes with tears?
What is the shape of a thought?

Can you recall one thought
you had yesterday?
Or one thought you had
two hours ago?