The Night the House Caught Fire - S1.E5

When Lydia comes down with a bad cold, John takes the opportunity to try to show her that people with vivid imaginations are better off than those who approach life from a more ""realistic"" point of view. The story of ""The Unicorn in the Garden"" doesn't seem to work, so John relates the story of his great-grandfather, who not only was a prolific storyteller but managed to get the fire department called out when he was trying to attend to young John's sniffles.