The following is from the journal of John Wesley.
A gentleman came to me full of good-will, to exhort me not to leave the Church; or (which was the same thing in his account) to use extemporary prayer, which, said he, “I will prove to a demonstration to be no prayer at all. For you cannot do two things at once. But thinking how to pray and praying are two things. Ergo, you cannot both think and pray at once.” Now, may it not be proved by the salf-same [sic] demonstration that praying by a form is no prayer at all? E.g. You cannot do two things at once. But reading and praying are two things. Ergo, you cannot both read and pray at once.” Q.E.D. [Entry on November 28, 1740]