These several lines from the essay

Are my sentences correct English?:

-These several lines from the essay by 18-century essayist Samuel Johnson are scintillating with wit and sparkling with wisdom. Johnson raises a very important question: what is biography for? This question prompts us into thinking another problem: what is literature for? What is the value of existence of literature? To me literature is extremely important, no less so when we compare it with such profitable and beneficial knowledge of medicine and law. Literature exists to increase the happiness of mankind, augment the felicity of the soul, and expand the pleasure of the mind; we may indulge ourselves in admiring a brilliant sentence, marvelling at a perfect analogy, and delighting in a perceptive remark. To this end, all writers should devote their energies. As long as they could produce good works that fulfil this requirement, they could be said to have contributed to the sphere of literature. When writing biography, writers should select all the useful materials that are instructive and pain-lessening. He who records the failure of an attempt should show the reader the path to success when the reader himself undertakes the task, which is instructive; he who put to paper a painful experience should convince the reader of the futility of working on the same line, which could be pain-lessening when the reader is clever enough to hold himself back. This is the use of biography.

Thank you.