Potpourri of comments about the fiber-optic gyro for its 40th anniversary, and how fascinating it was and it still is!

This 40th anniversary is the opportunity to recall how fascinating is the fiber-optic gyro with its potential perfection. Pure unaided strapdown inertial navigation yielding drift of less than one nautical mile in a month has been demonstrated in a laboratory. This paper also adds several comments about points that could be better known and should be outlined.