In historical Tantra, it was not enough simply to find a text and begin repeating the practice described in it.
Something else mattered more: who taught you?
Why Was Lineage Important?
A lineage is a chain of transmission from teacher to student.
A practitioner received knowledge from a guru, who had received it from their own teacher, and in this way the tradition connected present-day practitioners with earlier generations.
In many Tantric traditions, entry into such a lineage took place through initiation — diksha. Scholars regard initiation into a lineage of teaching and practice as one of the most important social features of Tantra.
Why Couldn’t Someone Simply Read a Book?
Because Tantric texts often assumed that the reader already understood the necessary context.
How should a mantra be pronounced? How should a ritual be performed? How should the symbols be interpreted? What was permitted, and what was forbidden?
These answers were expected to be transmitted by a qualified teacher. In some traditions, it was believed that without proper initiation, a person did not gain full access to the practice at all.
Lineage also served another important function — it established authority.
If a teacher claimed to have received knowledge through a recognized chain of transmission, this suggested that they had not simply invented their own system the day before.
Of course, the actual histories of lineages could be more complicated than the traditions themselves claimed. This is why historians carefully examine old lists of teachers and compare different versions of lineage accounts.
In historical Tantra, the question “Who is your teacher?” could sometimes be almost as important as the question “What do you believe?”