Can you provide the basis of the concept of "self-trust," individualism, which is a key for trancedentalist concepts (individual divity, imagination)?
In self-trust all the virtues are comprehended. Free should the scholar be—free and brave. Free even to the definition of freedom, “without any hindrance that does not arise out of his own constitution.” Brave; for fear is a thing which a scholar by his very function puts behind him. Fear always springs from ignorance. It is a shame to him if his tranquillity, amid dangerous times, arise from the presumption that, like children and women, his is a protected class; or if he seek a temporary peace by the diversion of his thoughts from politics or vexed questions, hiding his head like an ostrich in the flowering bushes, peeping into microscopes, and turning rhymes, as a boy whistles, to keep his courage up. So is the danger a danger still; so is the fear worse. Manlike, let him turn and face it. Let him look into its eye and search its nature, inspect its origin—see the whelping of this lion which lies no great way back; he will then find in himself a perfect comprehension of its nature and extent; he will have made his hands meet on the other side and can henceforth defy it and pass on superior. The world is his who can see through its pretension. What deafness, what stone-blind custom, what overgrown error you behold is there only by sufferance—by your sufferance. See it to be a lie, and you have already dealt it its mortal blow.
The basis for “self-trust” is essentially Emerson's definition and recurring theme of self-reliance. America was still a young country when Emerson was writing and he saw this as a time for America to define itself historically by establishing a political and philosophical ethos which would be supplemented and celebrated by an American literature and an American way of thinking. This would incorporate a break from the past because for a scholar to be self-reliant and to come up with new ways of thinking, he/she should avoid relying on past authors (particularly referring to America's European predecessors) for their own authentic voices. Emerson noted that consulting past authors and thinkers is kind of a plan B. Plan A is for man to first think for himself.
In fact, Emerson's philosophy of individualism and self-reliance was so bent on authenticity that he would also encourage an individual to be willing to contradict what he said yesterday. Indeed, he thought that relying on your own personal (self's) past is as stagnant as relying on the historical or social past. In Self-Reliance, he writes,
“A foolish consistency is the hobgoblin of little minds, adored by little statesmen and philosophers and divines. With consistency a great soul has simply nothing to do. He may as well concern himself with his shadow on the wall. Speak what you think now in hard words, and to-morrow speak what to-morrow thinks in hard words again, though it contradict every thing you said to-day. — 'Ah, so you shall be sure to be misunderstood.' — Is it so bad, then, to be misunderstood? Pythagoras was misunderstood, and Socrates, and Jesus, and Luther, and Copernicus, and Galileo, and Newton, and every pure and wise spirit that ever took flesh. To be great is to be misunderstood.”
In “The American Scholar,” Emerson expresses these same ideas. He also notes that epochs in history are defined by their difference from preceding epochs. Emerson is talking about this grand experiment that is America but he is doing so by encouraging the individual to have trust in him/herself. One who is self-reliant will not be mindlessly herded along by the course of history. A self-trusting individual will have the courage to embrace the freedom to think outside the historical box. That is, the self-trusting individual will have the courage to explore themes of the present epoch even if they seem more mundane than the glorification of past individuals, societies and works of art.
In short, Emerson wanted the American individual to trust himself by continuing to grow.