Long before the modern word, many sacred traditions spoke of souls joining, helping and moving between bodies. These are not the same as modern walk-in teaching, but they show how old and widespread the intuition is.
Kabbalah (Jewish mysticism)
Ibbur, meaning “impregnation” of the soul. In the teachings of Rabbi Isaac Luria (16th-century Safed), recorded by Rabbi Hayim Vital in Sha’ar HaGilgulim, a righteous soul can join a living person during their lifetime to help them grow, do good and complete their soul’s repair (tikkun). The helping soul is “enclothed” within the person’s own soul, and the two work together as one. The Zohar tells that the souls of Nadav and Avihu joined Pinchas.
The echo: A helping soul who joins out of love. Very close to the modern soul braid.
Kabbalah: levels of soul
Kabbalah teaches that the soul has levels: Nefesh, Ruach, Neshamah, Chayah and Yechidah. Each may arrive at a different stage of life, and souls belong to families called soul roots (shoresh neshamah).
The echo: Supports the idea that a soul can arrive in stages and receive gifts as it grows.
Hindu yoga
Parakaya pravesha, “entering another body”, is listed among the yogic powers in the Yoga Sutras of Patanjali (III.38). Tradition says the sage Adi Shankara entered the body of the departed King Amaruka to gain knowledge, then returned to his own body.
The echo: A conscious soul choosing to enter a body for a purpose.
Tibetan Buddhism: transference
Phowa and drong-jug, the transference of consciousness. Tradition tells that Darma Dode, son of the great teacher Marpa, moved his consciousness into a dove and then into a young boy in India, who became the revered teacher Tiphupa.
The echo: Consciousness continuing its path of service through another form.
Tibetan Buddhism: tulku
Tulku: recognized rebirths of awakened teachers who return on purpose to help others.
The echo: Like wanderers and volunteers: souls who choose to come back in service.
Christianity
Paul’s words: “If anyone is in Christ, he is a new creation; the old has gone, the new has come” (2 Corinthians 5:17).
The echo: Often quoted for the feeling of becoming new. Christian tradition itself reads it as spiritual renewal.
Shamanic traditions
Soul retrieval: lost soul parts return, bringing wholeness.
The echo: A parallel to aspect walk-ins and braids, where more of the soul arrives.
Ancient Egypt
The soul had many parts, including the ka (life-double) and ba (the traveling personality).
The echo: The soul as many-layered and able to move.