An excerpt from Pi: A Biography of the World's Most Mysterious Number:
Since Euler is the father of the symbol that has the title role of this book, we ought to take a glimpse into his interesting life history. Born in Basel, Switzerland, in 1707, he was initially taught mathematics by this father, who himself studied under the famous mathematician Jakob Bernoulli. This connection served him well, for as the father noticed his son's proclivity for the subject, he arranged for him to study with Jakob Bernoulli's son (also a famous mathematician) Johann Bernoulli.
How to understand the construction for as?