Page "Hindu deities" Paragraph 8

The Tridevi or triplet goddesses of Hinduism have equal importance as the trimurti.

Brahma is creator, so he needs knowledge or goddess Saraswati ( Vaak ) to create.

Vishnu is observer, so he needs the goddess of wealth and prosperity, goddess Lakshmi ( Shri ).

Finally, Shiva is destroyer and re-creator, so he needs goddess Parvati, Durga, or Kali for power.

Without the Tridevi, the Trimurti are not complete and vice versa. They are the active energy of the trimiurti without whom the Gods will lose their power to create, observe or destroy and re-create.

In other words, they will remain powerless. They are the various manifestations of Goddess Adi Parashakti, the Supreme mother.