Final answer:
Isaac Newton favored a corpuscular theory of light, which explained its straight-line behavior from a source. However, Thomas Young's double-slit experiment in the early 19th century provided evidence for the wave nature of light.
Step-by-step explanation:
Isaac Newton favored a corpuscular theory of light because he believed that its straight-line behavior from a source was better explained that way. He proposed that light was composed of streams of extremely tiny particles traveling at high speeds according to Newton's laws of motion. However, in the early 19th century, Thomas Young's double-slit experiment demonstrated optical interference, providing strong evidence for the wave nature of light.