We owe our access to Vincent van Gogh's thoughts and feelings about many of his paintings to:

A. the Van Gogh Research Society.
B. the research of Dorothy and Herbert Vogel.
C. the many letters he wrote to friends and relatives.
D. his autobiography.
E. None of these answers are correct.

C
The letters reveal a sensitive, intelligent artist pouring out his thoughts and were an important documentation of his life and art.