how did waltons trip begin as a dream during childhood

Walton says he once hoped to become a famous poet, but failed. Yet he has kept his childhood dream of reaching the North Pole. He adds that he could have lived his life in wealth and ease, but did not. For this reason, he feels that he deserves to “accomplish some great purpose.”

Here is a quote from the book,

"This expedition has been the favourite dream of my early years. I have read with ardour the accounts of the various voyages which have been made in the prospect of arriving at the North Pacific Ocean through the seas which surround the pole. You may remember that a history of all the voyages made for purposes of discovery composed the whole of our good uncle Thomas's library. My education was neglected, yet I was passionately fond of reading. These volumes were my study day and night, and my familiarity with them increased that regret which I had felt, as a child, on learning that my father's dying injunction had forbidden my uncle to allow me to embark in a seafaring life."