experiment
“Nothing is so good as an experiment which, whilst it sets an error right, will give the true experiment which ought to be believed.”
“Without experiment I am nothing.”
“The test of all knowledge is experiment. Experiment is the sole judge of scientific 'truth'.”
“If it disagrees with experiment, it's wrong. In that simple statement is the key to science.”
“ALL THIS IS A DREAM. Still examine it by a few experiments.”
“Nature is our kindest friend and best critic in experimental science.”