Here is a review of The Secret Teachers of the Western World from the Library Journal:
11/15/2015
Lachman (Evolution of Consciousness, California Inst. of Integral Studies; Politics of the Occult) presents this work as “a serious study of our ‘rejected knowledge’ and an engagement with some of the people pursuing it today” and successfully achieves his first goal of a scholarly study of the “rejected” knowledge of the Western esoteric tradition. This comprehensive history engagingly traces a way of thinking and living that was often at the margins of accepted Western society. While it would be easy to sensationalize such a past, Lachman deftly navigates between the extremes of presenting a unified “conspiracy” behind hermeticism and a polemical attack on its opponents. It is an academic work, not a practitioner’s guide, which ranges from discussions on Plato to Carl Jung and onto the New Age as well as current explorations in alternative spiritual traditions. Lachman further briefly considers important mystics from the Jewish, Christian, and Islamic traditions who informed the esoteric tradition. VERDICT This solid introduction to occult and esoteric history provides a sensible foundation for any reader who finds appeal in the current interest in participatory spirituality as distinct from simply holding specific religious beliefs.—Daniel Wigner, South Plains Coll., Lubbock, TX
Gary Lachman 
Have you ever read http://www.amazon.com/Secret-Teachings-Ages-Readers-Edition/dp/1585422509/ref=pd_sim_14_9?ie=UTF8&refRID=02RPZQ4GJVNSP9RGSGJX? Thoughts on comparison to this one if so? Thanks.
Yes I read Manly P. Halls’ classic years ago and go back to it now and then. I used to see Hall lecture at his Philosophical Research Society in Los Angeles in the 1970s. My book is more of a history.
I’m reading Inner Christianity right now and finding it to be in similar in tone to Manly’s. So many new Secret Histories, I think between Manly and others, this is a well covered tpic, but rather dense. I am working on a book of my own from a Gen X perspective, not scholarly though, but I’ll have to pick your book up now, thanks 😉
In relation to Gebser’s thought, you and your readers might find interesting a recent review posted at Surrealist NYC of George Sebbag’s 2012 book Potence avec paratonnerre. Surréalisme et philosophie. A couple of excerpts:
“[…] “Le temps sans fil is Sebbag’s collage of two closely related passages from André Breton’s ‘Introduction to the Discourse on the Poverty of Reality’ in Break of Day. Breton’s essay opens with a meditation on the place of the ‘sans fil’ (wireless) in our vocabulary and dreams, ‘one of the very few specifically new determinations of our minds.’ […] Sebbag asks how the sans fil</i] could inform Breton’s notion of time and finds an immediate response. 'If the new model of the ‘sans fil’ takes time for its object, then the representation of time changes. Time changes paradigm. The linear and monotone time of classical science, the ascending arrow of the Enlightenment, the dialectical and eschatological becoming of Hegel or Marx, all of these linear images of a quantified, continuous, or oriented time yield to the appearance of an antenna over a large surface, to return to the image of the ’sans fil’ rightly used by André Breton. The fil du temps (thread of time) cedes place to le temps sans fil.'
Considering how wireless technology has expanded, he continues: 'Wireless transmission with the aide of terrestrial antennas or satellites completely disconnects time from space. The instantaneous transmission of a live event radically autonomises time. For example, ten contemporaneous events can exist simultaneously on the same screen. In brief, one can say that of the two a priori forms of sensibility according to Kant, space and time, the first is reduced to the bare minimum and the other soars or takes flight. If we add on top of wireless transmission all the recording methods of cinema, disk, or computer, then the three modalities of time—past, present, and future—become manageable entities and interchangeable objects. With the appearance of artificial durations, notions sacralized by classical and modern spirits, such as historical chronology or the ages of life, are made laughable'."
P.S. Apologies for forgetting to post the link to the complete review of the Sebbag book for those who may be interested. It is here:
http://surrealistnyc.tumblr.com/post/142307260946/temps-sans-fil .
Also, apologies for the improperly closed italics HTML tag, above.