There are compelling reasons why the closed carbon dioxide filtration method for inhalation anaesthesia deserves serious reconsideration. Use of the closed absorption system today can provide all the benefits recognised by those who introduced it seventy to eighty years ago. A most important benefit is the increased opportunity of learning afforded the user, which leads either neophyte or senior clinician to improvement of both concept and clinical skills. The current resurgence of interest is fully appropriate for all physicians who aspire to be true specialists in the care of patients during clinical anaesthesia.