Christopher Reeve? David Michael Petrou? Clark Kent? Kal-El? Apocryphal?

Question for Quote Investigator: An actor who played Superman was asked about the enduring popularity of the character. The actor stated that the appeal was not based solely on power. Instead, true heroism was shown by the wisdom and maturity displayed while wielding power. Would you please help me to find the correct phrasing of this quotation and the identity of the actor?
Reply from Quote Investigator: An influential depiction of superheroism appeared in the 1978 film “Superman”. Producer David Michael Petrou published a companion book titled “The Making of Superman: The Movie” in the same year. Petrou spoke to actor Christopher Reeve who had been selected to play the role of Superman and his alter ego Clark Kent / Kal-El:1
As much as he looked the part, however, Chris made it clear when he talked to me later on the set that the film Superman would have to have greater depth of character than the comic-book figure.
Reeves continued his remarks with a statement about power:
So what I’m trying to do is to go way under. If the script calls for incredible feats, all I have to do is . . . just simply do them. What makes Superman a hero is not that he has power, but that he has the wisdom and the maturity to use the power wisely. From an acting point of view, that’s how I approach the part.
Below are additional selected citations in chronological order.
In November and December 1978, the quotation from Reeve achieved further distribution when it appeared in newspapers such as “The Commercial Appeal” of Memphis, Tennessee2 and in “The Honolulu Advertiser” of Honolulu, Hawaii:3
“What makes Superman a hero is not that he has power, but that he has the wisdom and the maturity to use the power wisely. From an acting point of view, that’s how I approach the part.”
The book “Current Biography Yearbook 1982” included an entry for Christopher Reeve which contained the quotation:4
“It’s important to humanize Superman. He walks through walls and can hold up the Golden Gate Bridge with his hands and so forth. So if on top of all that he said to himself, ‘My God, am I good!’ then you’d have a real prig, a boring piece of cardboard. . . . What makes Superman a hero is not that he has power, but that he has the wisdom and maturity to use the power wisely.”
Christopher Reeve died in 2004. The obituary printed in “The Washington Post” included the quotation:5
During 18 months of filming, beginning in March 1977, Reeve transformed himself physically and mentally into the Man of Steel.
“What makes Superman a hero is not that he has power, but that he has the wisdom and maturity to use the power wisely,” Reeve noted in the 1978 book “The Making of Superman” by David Michael Petrou.
In conclusion, Christopher Reeve deserves credit for this quotation. He spoke it during a conversation with David Michael Petrou, and it appeared in the book “The Making of Superman”.
Image Notes: Silhouette of a person from Javier García at Unsplash. The image has been cropped and resized.
Acknowledgement: Great thanks to the anonymous person whose inquiry led QI to formulate this question and perform this exploration.
- 1978 The Making of Superman: The Movie by David Michael Petrou, Chapter 5: The not-so-lovely month of May, Quote Page 83, Warner Books: A Warner Communications Company, New York. (Verified with scans) ↩︎
- 1978 November 24, The Commercial Appeal, Bullets, locomotives aside, will it fly? by Thomas Fox, Quote Page 20, Column 3 and 4, Memphis, Tennessee. (ProQuest) ↩︎
- 1978 December 29, The Honolulu Advertiser, Reeve: From ‘unknown’ to ‘super’ stardom – Part 5 of 5 by David Michael Petrou (Los Angeles Times), Start Page F5, Quote Page F6, Column 1, Honolulu, Hawaii. (Newspapers_com) ↩︎
- 1982, Current Biography Yearbook 1982, Edited by Charles Moritz, Person: Christopher Reeve, Start Page 351, Quote Page 353, The H. W. Wilson Company, New York. (Verified with scans) ↩︎
- 2004 October 12, The Washington Post, A Leading Man for Spinal Cord Research by Joe Holley (The Washington Post), Start Page A1, Quote Page A16, Column 1, Washington, D.C. (ProQuest) ↩︎