The indefinite adjective pronoun one when put in
place of a personal substantive is liable to raise confusion. When a sentence
or expression is begun with the impersonal one the word must be used
throughout in all references to the subject. Thus, "One must mind one's own
business if one wishes to succeed" may seem prolix and awkward, nevertheless it
is the proper form. You must not say—"One must mind his business if he
wishes to succeed," for the subject is impersonal and therefore cannot
exclusively take the masculine pronoun. With any one it is different.
You may say—"If any one sins he should acknowledge it; let him not try to
hide it by another sin."