For centuries, Indian women were forbidden from chanting Vedic Mantras, especially in public, out of fear the power of the religious verses might cause menstrual problems and difficulties in bearing children.
Though thinking changed slightly in recent years to allow women to chant in some cases, it remained extremely rare and private.
But on November 6, this will change.
A total of 108 Indian women has been selected to chant mantras in front of an audience of millions in the northern Indian town of Hardwar, part of ceremonies celebrating the centennial of a spiritual leader's birth.
And that will pave the way for women to chant mantras in other public events such as engagement, weddings and child-birth ceremonies.
It's a long overdue victory for women, especially in a country where women were not even allowed to hear the Vedic Mantras in ancient times, said Manju Agarwal, a psychology professor and women rights activist in Lucknow, northern India.
Known as Brahmavaadinis, or the ones who speak God's language, the women were carefully chosen and trained over six months for their unprecedented duty. The number 108 is auspicious in Hinduism.
The selection of the women was done through a rigorous process, in which they were tested for clarity of diction, accuracy in pronunciation and proper understanding of the Mantras, said Amrendra Singh, a follower of Gayatri Paravar, the organisation behind the ceremonies.
Most of the women are between 25 and 30 but a few are over 50, and a majority come from educated, well-to-do backgrounds.
In addition to breaking the taboo on women chanting the Vedas, the women will also perform sacred rituals known as yagya, in which herbs are poured into a fire while chanting mantras, that have also been forbidden to them up to now.
Among them are some women from tribal groups and Dalits, formerly known as Untouchables. Religious tradition has long forbidden members of these groups from chanting, no matter what gender they are.
The unusual stance is in line with the principles of Gayatri Pariwar founder Pandit Sriram Sharma Acharya, the anniversary of whose birth is being celebrated, group leaders said.
Throughout his life Acharya worked tirelessly towards extending equal rights to women, said Pranav Pandya, who heads the All World Gayatri Pariwar.
This mantra chanting by women in front of the public is a manifestation of that principle.
For the women involved, the reasoning is much simpler -- they are just glad to have the chance to chant.
Deena Trivedi had a Master's degree in Labour Welfare and took a government job, but left in search of something deeper.
I left my job in order to live life at a different and more evolved level, the 48-year-old said.
I am chanting mantras since then and I can see my personality has improved, with better concentration and more focus.
The five-day celebration in Hardwar is expected to see about 5 million people take part. Some 3,000 are likely to come from the organisation's branches around the world.
(Editing by Elaine Lies and Yoko Nishikawa)