Louis Pasteur? Apocryphal?

Question for Quote Investigator: Achieving your most vital objectives in life can be quite difficult. Reportedly, the famous French scientist Louis Pasteur once highlighted the personality trait that enabled his enormous success:
Let me tell you the secret that has led me to my goal. My strength lies solely in my tenacity.
Is this quotation genuine? Would you please help me to find a citation for the original French version of this statement?
Reply from Quote Investigator: In 1885 Louis Pasteur attended a banquet of veterinary surgeons who praised his remarkable accomplishments. During his speech Pasteur pointed to the attribute that facilitated his scientific breakthroughs. The following passage in French is from the seventh volume of “Œuvres de Pasteur”. Boldface added to excerpts by QI:1
Dans la vie, il faut consacrer tous ses efforts à faire le mieux possible ce à quoi on est apte. Et puisqu’on a tout à l’heure beaucoup parlé de mes études, laissez-moi vous dire le secret qui m’a mené au but. Ma seule force est dans ma ténacité.
Here is one possible rendering into English:
In life, you have to devote all your efforts to do the best you can. And since we talked a lot about my studies earlier, let me tell you the secret that led me to my goal. My sole strength is in my tenacity.
Below are additional selected citations in chronological order.
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