What destroys a Republic, and what unites it

 India has tremendous diversity---so many religions, castes, languages, regions, ethnic groups, etc. So to remain united we must know what our forefathers have taught us in this connection

" Bhedey ganaa vineshyanti, bhinnaastu sujayaah parah
Tasmaat sanghyaatayegen prayateran ganah sada "
i.e.
" Republics have been destroyed only because of internal divisions among its people.
It is only when there are internal divisions among the people that
an enemy can destroy it.
Hence a Republic should always try to achieve unity and good
relations among its people "
Bheeshma Pitamah's upadesh to Yudhishthir in Shantiparva of Mahabharata, Chapter 107/108, shloka 14.

" Palkuzhuvum paazhseyyum utpagayum
Vendalaikku kolkurumbum illadhu nadu "
i.e.
" That alone becomes a prosperous country
Which is free from separatist tendencies, and people
who harm its sovereignty "
Tirukkural by Tiruvalluvar, chapter 74, verse 5.

" Muppadhu kodi mugamudayal
Enil maipuram ondrudayal
Ival seppumozhi padhinetudayal
Enil sindhanai ondrudayal "
i.e.
" This Bharatmata has 30 crore faces
But her body is one
She speaks eighteen languages
But her thought is one "
Tamil poet Subramania Bharathi, 1910