Final answer:
Dr. Jekyll recognized the life of burden humans bear due to the constant inner struggle between good and evil, influenced by hereditary factors and societal pressures.
Step-by-step explanation:
Dr. Jekyll felt that man is doomed to lead a life of burden because of the inherent dual nature of humanity, struggling between virtue and vice. His contemplation reflects on the weight of hereditary evil and the inexorable presence of an individual's darker side, regardless of one's conscious desires. The quotes from various texts suggest that this burden is not only a personal struggle but can also be seen as a metaphor for larger societal issues such as racial oppression, personal fulfillment, and moral conflict. Characters such as McTeague, the protagonists in the works of W.E.B. Du Bois, and Young Goodman Brown reveal that individuals often face the challenge of recognizing and overcoming the innate and external obstacles that life presents.