RT Journal A1 PORTER WT T1 THe critical periods in the life of a physician JF Journal of the American Medical Association JO Journal of the American Medical Association YR 1909 FD April 24 VO LII IS 17 SP 1305 OP 1307 DO 10.1001/jama.1909.25420430001001 UL http://dx.doi.org/10.1001/jama.1909.25420430001001 AB The life of a man is marked by certain critical periods. Birth, marriage and death are commonly so reckoned. Their importance, as conventionally defined, is chiefly historical. In this conventional form they may be regarded as erroneous concepts developed during the lamentable and prolonged darkness which preceded the advent of the biologist. We now know that birth and death are inseparable companions. They begin together long before that change of habitat which we ordinarily call birth, and they go on together even after death has plainly the upper hand. What have we, as rational beings, to do with these processes? Nothing. We are born blank. Of death we know even less than of birth. Ages before the Pharaohs, death came mysterious, unsolved, and still so comes. We have no personal data of birth because we are born without the powers of observation and reason. And we have no data regarding