My answer to this was the following, interpolated with some notes that came to my mind while preparing this post: Cosmic consciousness and Union with the ALL, as well as Immortality, is the birthright of every human. But there exists a particular set of techniques that may facilitate this birthright better than the slow and normal processes of Nature. These techniques, which mimics the way of Mother Nature but at the same time enhances it, constitutes a tradition and thus a lineage. Lineage, passed from a true initiator to the initiate, also confers direct changes of consciousness; this should be the case in all genuine initiation, also that of the Golden Dawn in the Outer, although changes in the latter are more subtle compared to initiations of a higher degree or arc.
Note: This fact is the reason why almost all of the yogic and tantric Far Eastern brethren emphasise the significance of correct lineage, tracing it back to some mythical figure or demi-god in the ancient past. The first thing that finds the newly initiated student is the narrative of the chain of past masters. Especially made mandalas containing a list of these (see image at the head for an example) are provided to the student to meditate upon to adjust his mind to the mindset of past masters and egregore. The Sufi orders of the Near Eastern brethren places equal emphasis on lineage; the student becomes humbled by the fact that by the hand placed upon him by his initiator he feels the grip of all the past masters back to Mohammed himself. In continental Europe a similar concept of lineage is a natural part of the Lodge culture in the different Martinist and Rosicrucian bodies.
This scorn against the notion regarding importance placed in lineage is a quite recent phenomenon and may almost be entirely restricted to the Anglo-Saxon domain or English speaking nations, although not if you trace your history further back than to the 1960’s when the old books by Aleister Crowley and Israel Regardie were repulished and widely circulated, serving as the source for the establishment of new Golden Dawn Temples without any trace back in history. Thus today it is politically incorrect in the Golden Dawn Community to claim any lineage whatsoever, because of this situation, and any such suggestions immediately becomes ridiculed by the reconstructionalist cohort.
But I must emphasize that there exist several different traditions (although they are not that different in essence, only in culture and language) which are probably equally effective, both in the West and the East. The particular tradition that the H.O.G.D./A+O teaches in its higest Grades is part of the Western Hermetic Alchemical Tradition, which has many similarities with Hindu and Tibetan Tantra and Daoist Internal Alchemy; there are some differences but many similarities – they are all part of the Alchemical Tradition. But Cosmic Consciousness and Union with the ALL, and perhaps even conscious Immortality, may be achieve by other means as well, such as contemplative mysticism and Theurgy. However, those who have experienced the true Alchemical Tradition (both Occidental and Oriental) knows that its formulae of energetic manipulation and transmutative powers of matter are second to none.
Note: Furthermore there exists several different European bodies within the Hermetic tradition of the Occident that do possess these mysteries, or at least parts of it. But in the Golden Dawn Community these higher and traditional teachings are extremely rare, with some few exceptions, not because it’s not accessible to them but because most teachers and leaders with an reconstructionalist bent aren’t at all intersted in it or even doesn’t believe it exists; they are suffering from a blind spot.
So in the final analysis, the querent in part was right that the mysteries of the ALL talks to us all through Nature. But I hold that there also exists man made formulae, based upon millennia of experience amongst a long chain of initiates, and highly evolved teachers which can provide a species of “short cut” to experiencing states of consciousness which are the innate part of Nature. This formulae are conferred through lineage, both in the Occident as well as in the Orient.