The greatest mistake in clinical medicine may be the desire to banish uncertainty. Healthcare professionals should be thorough and prudent when performing examinations and ordering diagnostic tests. The question is to act or not to act. The deeper question is whether there has been a loss of clarity about what is appropriate and necessary. An example is the case of a relative on a routine eye examination without complaints. The optician suspected temporal arteritis, which was the subject of a major educational article with DOI 10.1136/bmj-12. This led to an emergency meeting the next day. The GP wasn't too worried but thought it best to go ahead.