In Dr. Jekyll and Mr. Hyde, science becomes a cover and justification for supernatural activities. Dr. Jekyll ostensibly derives his potion in some sort of scientific manner as opposed to finding a magical amulet or something that releases evil as you might find in other stories. Dr. Jekyll’s brand of science, however, veers towards the "transcendental" (indeed, supernatural), while Dr. Lanyon adheres to a more traditional set of scientific notions. This disagreement causes an irreparable rift in their relationship, especially after Dr. Lanyon witnesses Dr. Jekyll’s transformation with his own eyes.
The physical transformation of Dr. Jekyll into Mr. Hyde – albeit scientifically impossible – is a premise necessary to fully exploring the idea of good and evil warring in one man’s breast.