A Capital should begin: (1) the first word of every sentence, and of every
line of poetry; (2) proper names of persons, places, months, and days; (3)
all appellations of the Deity; (4) titles of honor; (5) names of things
personified; (6) names denoting the race or nation of individuals; (7)
adjectives derived from proper names; (8) the first word of a direct
quotation or speech; (9) the principal words in the titles of books; (10)
words denoting important events, the chief subject of a composition, etc.
(11) The pronoun I and the interjection O are always capitals.