Pioneers are people who are the first or among the first, to enter a place, a field of inquiry or progress.
Pathfinders are people who go ahead of others into uncharted territory to discover the way or find new routes.
In the context of the paragraph, "It is an era which calls for action and for the best efforts of all those who would test the unknown and uncertain in every phase of human endeavor. it is time for pathfinders and pioneers."
He strives to vividly showcase the negative implications of capitalism by painting the mirage that is the American dream in contrast to the reality of wage slavery.
