What's actually happening
Neptune takes about 165 years to complete one circuit of the zodiac, spending roughly 14 years in each sign. Sagittarius is a mutable fire sign ruled by Jupiter. The Neptune in Sagittarius transit that ran from roughly 1970 to 1984 is the astrological background of the New Age movement, the globalization of spiritual practice, and the generation born into those themes.
What the tradition makes of it
Neptune in Sagittarius dissolves the boundaries between spiritual traditions. The religious form becomes secondary to the spiritual experience itself; what any tradition offers in the way of transcendence and direct encounter is sought across boundaries of culture and heritage. The spiritual journey is quite literally a journey — to teachers, to sacred sites, to traditions outside the inherited one.
The tradition notes this transit as producing genuine cross-cultural spiritual flowering and, in its shadow, the spiritual tourism that takes the form without the commitment — the superficial borrowing that consumes the sacred rather than participating in it.
How to actually use it
Take the spiritual quest seriously, and take the tradition you are drawing from seriously. The access to multiple wisdom traditions that Neptune in Sagittarius makes available is a genuine resource; what it requires in return is genuine engagement rather than appropriation or sampling.
When in doubt
What practice are you committed to — not just interested in, but actually practicing?