Answer:
They stress Columbus's determination and fearlessness.
Explanation:
The poem that has "Sail on! sail on! sail on! and on!" in it is called <em>Columbus, by Joaquin Miller</em>.
"Sail on" is a refrain in the poem to enforce the idea of exploration, braveness, and adventure. Columbus is going to a new world and he is not afraid to do so.
<em />
<em>These very winds forget their way, </em>
<em> For God from these dread seas is gone. </em>
<em>Now speak, brave Admiral, speak and say”— </em>
<em> He said: “Sail on! sail on! and on!”</em>
