As the saints and prophets were often forced to practise long vigils and fastings and prayers before their ecstasies would fall upon them and their visions would appear, so Virtue in its purest and most exalted form can only be acquired by means of severe and long continued culture of the mind. Persons with feeble and untrained intellects may live according to their conscience; but the conscience itself will be defective. … To cultivate the intellect is therefore a religious duty; and when this truth is fairly recognized by men, the religion which teaches that the intellect should be distrusted and that it should be subservient to faith, will inevitably fall.
p. 540. - The Martyrdom of Man (1872)