Based ,like all the Guitry movies of the era, on one of the playwright's work ,"Mon Père Avait Raison" ,despite moments of unquestionable brilliance,is a desultory even a bit confusing work.One sees little of the writer's genius which produces such classics as "LES Perles De LA Couronne" or "La Vie D'Un Honnête Homme" .
The scene between Guitry and his father already shows,in 1936,the fear of getting old (which would be even more obvious in such works as "Debureau" or even the Maintenon/Louis XIV scenes in "Si Versailles M'Etait Conté" ) and of dying ;the father revealing he tells all the people around he is older than he really is ,it's a scene which is not anodyne but is more a way of deceiving death (later the search for immortality would be a permanent feature in the director's works)than interest in his appearance.
Another remarkable scene shows Guitry's unfaithful wife who succeeds in proving him she has always been faithful (for she was true to her lover till he died), Reductio Ad Absurdum,one of Guitry's forte.
Father may be right ,father knows best ,but father is going to die ,so Carpe Diem!It's a happy end ,provided you don't know Guitry's later works.