The definition of the Argyll Robertson pupil is usually given as a condition in which the pupil does not respond to light but does respond in accommodation and convergence. There are those who hold that the light reflex must be entirely abolished and who do not recognize this phenomenon if any light reaction is preserved. While this may conform to the conception attributed to Argyll Robertson, it is a source of error. It must be assumed that the loss of the light reflex has been complete from the beginning, and this would imply an abrupt onset of the symptoms. In this method of reasoning, all preliminary stages to the production of an Argyll Robertson pupil are ignored. It is sometimes stated in an ophthalmologic report that the pupil does not respond to light, but does respond in accommodation and convergence without any reference to the manner in which the light