While Darrin, Samantha and Endora are browsing through an antiques store, Endora believes it's time Darrin suspected that Samantha may not be as young as her mortal equivalent would be. Without Samantha's knowledge and without Darrin's knowledge of the source, Endora does so by making available to him at the store a 17th century photograph of someone who looks like Samantha. Endora bolsters this issue by making Darrin feel like an old man, highlighting not only that Samantha may be centuries older than him, but also when he becomes an old man, she will probably still look like she does now, a beautiful young woman. Samantha is aware that Darrin is curious about the truth, but she has no idea the extent to which he knows the truth. As Darrin contemplates his future with Samantha under these circumstances, Samantha has to figure out a way to save her marriage if the truth truly does comes to light.
—Huggo