Complex sentence: In 1779 Phi Beta Kappa expanded to include chapters at Harvard and Yale, however, by the early 19th century the organization transformed itself into a scholastic honor society and abandoned secrecy.
Split into simpler sentences: In 1779 Phi Beta Kappa expanded to include chapters at Harvard and Yale. By the early 19th century, the organization transformed itself into a scholastic honor society and abandoned secrecy.