As cliché as this phrase would sound, I had the luxury of learning it from practice rather than from hearing. I spent 3 years of my life working on optically pumped vapor cesium magnetometers in the nEDM (neutron Electric Dipole Moment) experiment at PSI. For almost 10 years, it was believed by experts that cesium magnetometers are absolute magnetometers, with 100% accuracy, and it was believed that a magnetometer is only limited by its sensitivity. This was believed in an experiment where the relative precision of the measurement required is $10^{-10}$. After spending three years with this belief, which was as long as 10 years for others in my group, and while I was investigating another quantum mechanical effect called "The Quadratic Zeeman Effect", I stumbled upon an effect that relates the laser power to an absolute shift that could reach 100 pT; which is a relative accuracy shift of $10^{-4}$. Yes, 6 orders of magnitude were omitted for all those years, just because an inherited belief was carried on from one person to the other; with no experimental measurement that proves that cesium magnetometers are really absolute magnetometers. Although I left religions long years ago, where I realized back then that faith never leads to anything related to the truth; I never realized that faith could find its way into my life again, in some other way. Opposing faith while seeking the truth about reality is one of the greatest challenges a researcher could face. One would never realize where faith could sneak into your science career to ruin something you're doing. Be aware of it! Cheers, I learned my lesson :)