WHEN, in compliance with the request of our President, I consented to speak on the life of Roentgen, it seemed to me that more vital and interesting than merely to review the events of his life would be to study his character and personality and the bearings these had on his scientific labors, and to consider his career from the standpoint of the light it throws on the spirit of the age and the lesson it carries to even the humblest worker. It is as difficult, says Strachey, to write a good life as to live one, but so striking is the personality of Roentgen, so inspiring his life's story, that the task invites performance. It is always of interest to study a great man with a purpose of seeking out the impelling motives of his life, the springs of his actions, his aims and endeavors; it is instructive to analyze the events which guided his life into those channels of human activity wherein he achieved fame, to fathom by what odd chance, what shifts and struggles, what combination of circumstances and character played a part in his arrival at distinction. Roentgen grew up in die very seedtime of progress, coming to the full bloom of maturity with the first onrush of modern science and living long enough to witness its tremendous victories and the complete revolution of scientific thought. And what a revolution it has been! How striking the contrast between the self-satisfied complacency of the physical world before Roentgen's discovery, regretting there were no more worlds to conquer, and the feverish activity in the endless paths, now but dimly envisioned, leading to regions containing truths tremendous in their import to humanity. Wilhelm Conrad Roentgen was born in Lennep in the Rhineland on the 27th of March, 1845, and died on the 10th of February, 1923. In his famous essay, “Concerning Human Understanding,” Locke tells us that the child's mind is essentially a blank tablet upon which nothing is written, and that all knowledge rests on experience. Let us, therefore, pause for a moment to consider the childhood of the character we are studying. What were the childhood experiences, influences and relationships, which definitely moulded his character? Since parental images are the models engraved on the growing mind which serve as standards and determinants in later life and influence adjustments in the workaday world, it is interesting to note that he was an only child of a German father and Dutch mother. It has been pointed out that, properly brought up, the only child possesses attributes which tend to leadership, and some of the greatest leaders in all walks of life were only children. Roentgen's childhood was a very happy one and was spent in Utrecht, Holland, the birthplace of his mother. His father, Frederich Conrad, was a farmer, a man of the soil, simple, reserved, taciturn and religious. From him he inherited the qualities of industry, of patience, of directness of action and perseverance in life's efforts and strivings.