What I find most intriguing in McKenna's chart is that it isn't the chart of a scientist at all - it's more the chart of someone who would make
cultural impact, as he did. His Libra-Leo luminaries are striking because of their relationship to the Libra-Aquarius luminaries of Timothy Leary, with whom he's understandably compared. If this were the old heyday of monthly astrology magazines, a great article would have been a character-biography vs. chart comparison of McKenna and Leary, who shared the same Sun-sign and had opposite Moon-signs.
While none of these signs seems immediately obvious for the main areas identified with McKenna, I suggest digging through the detailed sign breakdowns here:
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viewtopic.php?f=13&t=34#p146
For example, just off the top of my head, other than the Libra tendency to have
social (cultural) impact most - consider Libra Bill Gates, whose chart only secondarily speaks of technology but who dramatically altered our entire culture - there is also the Libra connection to environmental activism and natural draw to the Old Religion, something that comes through McKenna's work quite clearly. With a Libra Sun plus Venus conjunct Sun and about 1° from Ascendant, his chart is primarily Venus-themed - it's the planet through which the rest of the chart finds expression.
Without digging too deeply, I see his Leo Moon as mostly reflecting his presentation style and the way he leveraged his personality to attract attention. Combined with the rising Mercury-Mars conjunction, it gave a forceful presentation. I think if you dig through the Leo Moon breakdowns, you'll find more.
One terribly intriguing detail of his chart is the role of Eris. McKenna had a Neptune-Eris opposition - hardly a thing to distinguish him (but it's closer mundanely, under 3°, than ecliptically). It seems clear that McKenna's Neptune is a significant part of his basic character and destiny. My first-attempt articulation of Neptune-Eris aspects is OK for him, but by no means captures him directly; it is, "Unleashing the chaos, letting it flood (living amidst a chaos storm, surfing the wave of uncertainty)." Not bad, I suppose, but not individually.
However, if Eris is taken as a valid chart factor, the Neptune-Eris opposition anchors the most important aspect aspect structure in his chart: His Neptune sextiles both ends of a trine between Saturn and Mars (with Pluto and Mercury around) but, adding Eris, it forms a classic "kite" formation. A full analysis of his chart should probably dig deeply into this with all its subtleties. Here's an aspect map of his chart to make these dynamics clear:
McKenna map.png
His closest aspect is Mercury trine Eris, 43'. There are a lot of Mercury aspects in the chart, so it might be hard to filter one out from the others, but my current "working interpretation" for Mercury-Eris aspects is:
Insight comes easily: Mind can manage vast arrays of data points, incorporating facts and evidence, leaping to significant, persistent success. (Seems intuitive at first impression, but actually pursues goals through persistent effort and skill rewarded by insight.) A sassy, often unbounded “think-for-oneself” way through life (may use shock tactics to prove they think and act on their own). Promiscuous: persistently casual, diverse, and indiscriminate in sexual variety (sliding through chaos? leaving a wake of chaos? “multiplicity” theme?).