Former Illinois Senate President Philip Rock, who served as the chamber's Democratic leader from 1979 to 1993, died Thursday. 

Rock was 78-years-old and had been diagnosed with Lewy body dementia.

Senate President John Cullerton (D-Chicago) released the following statement upon news of Rock's death on Friday:

When I was appointed to the Senate in 1991, Phil Rock was the Senate President. He took me under his wing, showed me the ropes and couldn't have been nicer about it. He was THE most articulate orator of anyone I've ever served with, a talent he told me he learned in the seminary.

It is with great sadness and respect that I mourn the passing of Phil Rock, a loyal servant of his constituents in Oak Park and on the West Side of Chicago, and for 12 years president of the Illinois Senate. Phil Rock was a man dedicated to the advancement of Democratic principles, unafraid to take unpopular stands for equality and justice, yet well versed in the necessity of bipartisanship. After his retirement from the Senate, his commitment to sound and compassionate policy continued through his work with higher education and his advocacy for Illinoisans with disabilities. His legacy is one of many reasons I am honored to serve as Senate president today, and his example will continue to guide our deliberations. I wish his family peace, comfort and encouragement at this difficult time.

House Speaker Michael Madigan (D-Chicago) also said he was "deeply saddened to learn of the passing of former Senate President Phil Rock." 

"He was a great friend, mentor and member of the General Assembly for many, many years. His accomplishments, especially in the area of bettering the lives of children, are legion," Madigan said. "Shirley and I join with his many friends and colleagues in offering sympathy and prayers to Sheila and their children for comfort and strength in these difficult times."