Your world is as big as you make it
I know for I used to abide
In the narrowest nest in a corner
My wings pressing close to my eyes.

It continues on with --

But I sighted the distant horizon
Where the skyline encircled the sea
And I throbbed with a burning desire
To travel this immensity.

I battered the cordons around me
And cradled my wings on the breeze,
Then soared to the uttermost reaches
With rapture, with power, with ease!

Written by Georgia Douglas Johnson (1880-1966)

The very first line is the core truth.