In an attempt to save their dying civilization, its leaders use time travel to fetch Sir Thomas More (chosen for his fine legal and moral sense) from shortly before his death in the year 1535 to be the president of Astrobe.

"[2] Judith Merril praised Past Master as "a complex, subtle, colorful, and highly sophisticated book", saying that "Lafferty magics me with humor, anger, and love, and with unpredictable corner-of-the-eye perspectives and perceptions, but above all, I suspect, with his word-music.

"[3] Algis Budrys criticized the book for not being longer because it did not depict More's thoughts, but concluded "It is good to see this kind of thing being written".

[4] P. Schuyler Miller declared the novel showed Lafferty "writing like the heir to 'Cordwainer Smith', yet always completely himself -- more macabre, more cryptic, with more of the humor of the incongruous [that] Samuel R. Delany calls 'ultraviolet' on the cover.

"[5] Alexei Panshin found Past Master "an eccentric, idiosyncratic minor masterpiece", saying "it has all of Lafferty's usual color and pyramiding of manic invention" as well as offering "easily the most real immediate problem of spiritual agony yet seen in science fiction".