My main authority?

Does "My main authority" mean "my major authoritative evidence"?

Context:

In The Life of Brian, one of the many things the Monty Python
team got right was the extreme rapidity with which a new religious
cult can get started. It can spring up almost overnight and then
become incorporated into a culture, where it plays a disquietingly
dominant role. The 'cargo cults' of Pacific Melanesia and New
Guinea provide the most famous real life example. The entire his-
tory of some of these cults, from initiation to expiry, is wrapped up
within living memory. Unlike the cult of Jesus, the origins of which
are not reliably attested, we can see the whole course of events laid
out before our eyes (and even here, as we shall see, some details are
now lost). It is fascinating to guess that the cult of Christianity
almost certainly began in very much the same way, and spread
initially at the same high speed.
My main authority for the cargo cults is David Attenborough's
Quest in Paradise, which he very kindly presented to me. The
pattern is the same for all of them, from the earliest cults in
the nineteenth century to the more famous ones that grew up in the
aftermath of the Second World War. It seems that in every case
the islanders were bowled over by the wondrous possessions of the
white immigrants to their islands, including administrators, soldiers
and missionaries. They were perhaps the victims of
(Arthur C. Clarke's Third Law, which I quoted in Chapter 2: 'Any sufficiently
advanced technology is indistinguishable from magic'