Prove all things
The first time I stepped into the McGill Schulich Science and Engineering library was in high school. I was looking up material for my science fair project, a study of conductance quantization in gold wires under the mentorship of not-yet-Dr. Alex Wlasenko and Prof. Peter Grutter at the McGill Physics Department.
Navigating around the library in search of QC's and QD's, one space would always catch my attention: adjacent to the main staircase on the first floor was a large table next to an imposing, unused fireplace. Engraved on the mantelpiece was the phrase: "Prove all things". At the time I must have been too young to appreciate the inscription.
A few years later, during my undergraduate studies at McGill, my classmates at I would often study together on the fifth floor of the Schulich Library and I would regularly walk pass the staircase and its fireplace. I read the engraving as a command to maintain intellectual honesty and rigour in my work. After all, I was pursuing a joint honours degree in physics and mathematics and I was very aware of the importance of proofs.
Eventually, I learned about the motto of the Royal Society of London, "Nullius in verba", take nobody's word for it. The founders had decided, in the 17th century, that facts derived from experiment and observation superceded dogma and fiat. I'd like to think that "Prove all things" was engraved with a similar purpose in mind.
As I matured as a research scientist, the Schulich library epigraph gained deeper meaning. It served as a reminder of the role and responsibility of scientists to use rationalism and skepticism in our research, to build a strong foundation from which further knowledge and insight can be derived, and to persevere to understand all aspects of our physical universe.
Addendum: I should note that the building that the library is housed in today used to be the MacDonald Physics building. This is where Ernest Rutherford conducted his experiments in atomic physics. I believe the basement is still radioactive.