This effect of others upon the speaker is especially expressed in the monologue, particularly in examples of a popular and humorous character.
While the monologue is the accentuation of some specific attitude of one human being as modified by contact with another, in a letter the attitude toward the other person is usually prolonged, due to past relationship; is more subjective, and expressed without any change caused by the presence of the person addressed. In some very animated letters, however, the attitude of the future reader's mind is anticipated or realized by the writer, and there is more or less of an approximation to the monologue. At any rate, this realization of what the other will think colors the composition. Letters are animated in proportion as they possess this dramatic character, and are at times practically monologues.
The skilful writer of a monologue omits obscure references in words to the sneers and looks of the hearer, except those which directly change the current of the speaker's thought. All must centre in the impression made upon the character speaking. In conversation, at times, a talker becomes more or less oblivious of his companion, yet the presence of his listener all the time affects the attitude of his mind.
If we render a letter artistically to a company of people, we necessarily turn it into a monologue. We read the letter with the person in our mind, as a listener, to whom it is directed. We do not give its deeper ideas and personal or dramatic suggestions to a company as a speech.
It is not surprising to find many monologues in epistolary form. Browning's "Cleon," in which is so truly presented the spirit of the Greeks,--to whom Paul spoke and wrote and among whom he worked,--is a letter written by Cleon, a Greek poet, to King Protus, his friend. Protus has written to Cleon concerning the opinions held by one Paulus, a rumor of whose preaching of the doctrine of immortality has reached him. "An epistle containing the strange Medical Experiments of Karshish, the Arab Physician," is a letter from Karshish to his old teacher describing the strange case of Lazarus with an account of an interview with him after he had risen from the dead.