Galen was keenly alive to the need of exactness in weights and measurements. He often criticizes past writers for not stating precisely what ailment the medicament recommended is good for, and in what proportions the ingredients are to be mixed. He also frequently complains because they do not specify whether they are using the Greek or Roman system of weights, or the Attic, Alexandrine, or Ephesian variety of a certain measure.[629] Moreover, he saw the desirability of more accurate means of measuring the passage of time.[630] When he states that even some illustrious physicians of his acquaintance mistake the speed of the pulse and are unable to tell whether it is slow, fast, or normal, we begin to realize something of the difficulties under which medical practice and any sort of experimentation labored before watches were invented, and how much depended upon the accuracy of human machinery and judgment. Yet Galen estimates that the chief progress made in medical prognostication since Hippocrates is the gradual development of the art of inferring from the pulse.[631] Galen tried to improve the time-pieces in use in his age. He states that in any city the inhabitants want to know the time of day accurately, not merely conjecturally; and he gives directions how to divide the day into twelve hours by a combination of a sun-dial and a _clepsydra_, and how on the water clock to mark the duration of the longest, shortest, and equinoctial days of the year.[632] [Sidenote: Psychological tests with the pulse.] Delicate and difficult as was the task of measuring the pulse in Galen’s time, he was clever enough to anticipate by seventeen centuries some of the tests which modern psychologists have urged should be applied in criminal trials. He detected the fact that a female patient was not ill but in love by the quickening of her pulse when someone came in from the theater and announced that he had just seen Pylades dance. When she came again the next day, Galen had purposely arranged that someone should enter and say that he had seen Morphus dancing. This and a similar test on the third day produced no perceptible quickening in the woman’s pulse. But it bounded again when on the fourth day Pylades’ name was again spoken. After recounting another analogous incident where he had been able to read the patient’s mind, Galen asks why former physicians have never availed themselves of these methods. He thinks that they must have had no conception of how the bodily health in general and the pulse in particular can be affected by the “psyche’s” suffering.[633] We might then call Galen the first experimental psychologist as well as the first to elaborate the physiology of the nervous system. [Sidenote: Galen’s anatomy and physiology.]