McLuhan's son, whom Cameron and Bob treat in dialogue 24 as a "barometer of the modern age" and a private key to the late work. Cameron infers that McLuhan could not bring his thought "to any kind of understanding" within his own family — the family's drift from Catholicism the evidence — and that watching Michael grow up drove much of McLuhan's thinking in the 1960s and 70s. Bob locates this in the period of Michael's New York drug arrest, when McLuhan's letters show him "really trying to figure out... what happened to his son."
Across the dialogues
Enters as the barometer — McLuhan's son, whose growing up (and New York drug arrest) Cameron and Bob read as a private key to the late thought
Michael is read as a hidden engine of the late McLuhan — his coming of age, more than any doctrine, is what Cameron thinks McLuhan was trying to understand through the 1960s and 70s, a "barometer" of the age within his own household.
"one of the keys to McLuhan thought in the 60s and 70s is just Michael sort of growing up."
Bob dates the strain to Michael's New York drug arrest, whose fallout McLuhan worked through in private correspondence "trying to figure out... what happened to his son" — the family rupture behind Cameron's inference.
"that's in that period when Michael got in trouble for the dope bust or whatever it was that happened, I think, in New York City."
Connections
Cameron reads Michael's growing up as a key to McLuhan's late thought; Bob places the "dope bust" in that period.