Just as a word means little out of context, a new observation or discovery needs a proper context in which to fit in order to be most meaningful. In other words, the mind must be prepared to receive the germ of a new idea. Discovery, like learning, is a phenomena that takes place in the human brain. The brain configures an event as a new pattern based on previous assumptions that were present at the onset of the event. You create the lucky accidents.
Many scientists agree with that position.
It was at this time that written records describe the use of molds and fermented materials as therapeutic agents. It was not until the late nineteenth century that progress was made on this front and a concerted effort was made to identify and isolate substances that would inhibit or destroy the causative agents of known human diseases. In the late 1800's bacteriologists and microbiologists set out to identify substances with therapeutic potential. These studies of contaminated cultures led to a series of observations by late 19th century bacteriologists and microbiologists describing the effect of mold on bacterial growth. Lister unsuccessfully attempted to identify the agent in the mold which inhibited bacterial growth.