“Essential for Necessary. This solecism is common among the best writers in the country and England. ‘It is essential to go early’; ‘Irrigation is essential to the cultivation of arid lands’ and so forth. One thing is essential to another thing only if it is part of the essence of it—an important and indispensable part of it, determining its nature, the soul of it.”
Excerpted from: Bierce, Ambrose. Write it Right: A Little Blacklist of Literary Faults. Mineola, NY: Dover, 2010.