The portrait of Pasteur with his granddaughter (Fig. 92) gives a touch of personal interest to the investigator and the contestant upon the field of science. His strong face shows dignity of purpose and the grim determination which led to colossal attainments; at the same time it is mellowed by gentle affection, and contrasts finely with the trusting expression of the younger face.
Pasteur was born of humble parents in Dôle in the Jura, on December the 27th, 1822. His father was a tanner, but withal, a man of fine character and stern experience, as is "shown by the fact that he had fought in the legions of the First Empire and been decorated on the field of battle by Napoleon." The filial devotion of Pasteur and his justifiable pride in his father's military service are shown in the dedication of his book, Studies on Fermentation, published in 1876:
"To the memory of my Father,
Formerly a soldier under the First Empire, and Knight of the Legion of Honor.
The longer I live, the better do I understand the kindness of thy heart and the superiority of thy judgment.
The efforts which I have devoted to these studies and to those which have preceded them are the fruits of thy example and of thy counsel.
Desiring to honor these precious recollections, I dedicate this book to thy memory."
When Pasteur was an infant of two years his parents removed to the town of Arbois, and here he spent his youth and received his early education. After a period of indifference to study, during which he employed his time chiefly in fishing and sketching, he settled down to work, and, thereafter, showed boundless energy and enthusiasm.
Pasteur, whom we are to consider as a biologist, won his first scientific recognition at the age of twenty-five, in chemistry and molecular physics. He showed that crystals of certain tartrates, identical in chemical composition, acted differently upon polarized light transmitted through them. He concluded that the differences in optical properties depended upon a different arrangement of the molecules; and these studies opened the fascinating field of molecular physics and physical chemistry.
Pasteur might have remained in this field of investigation, but his destiny was different. As Tyndall remarked, "In the investigation of microscopic organisms—the 'infinitely little,' as Pasteur loved to call them—and their doings in this, our world, Pasteur found his true vocation. In this broad field it has been his good fortune to alight upon a crowd of connected problems of the highest public and scientific interest, ripe for solution, and requiring for their successful treatment the precise culture and capacities which he has brought to bear upon them."