Emerson's tone is radiant, self-assured, and boundlessly optimistic. From the introductory poem at the beginning of the essay, Emerson is clear about the possibility of the unlimited potential of the human mind:
I am the owner of the sphere,
Of the seven stars and the solar year,
Of Caesar's hand, and Plato's brain,
Of Lord Christ's heart, and Shakespeare's strain.
His ecstasy is understandable, if he feels that humanity has an infinite capacity to create—and to harness the past creations of great thinkers and writers. Emerson spends much of "History" celebrating these capacities:
There is one mind common to all individual men. Ever man is an inlet to the same and to all of the same. He that is once admitted to the right of reason is made a freeman of the whole estate. What Plato has thought, he may think; what a saint has felt, he may feel; what at any time has befallen any man, he can understand.
This is the tone of revelation with which Emerson urges the reader to take up the task of envisioning humanity as a complex tapestry of individuals who are nonetheless united in their human condition. If we can understand each other, Emerson argues, then we have to try to do so.