A very small cause which escapes our notice determines a considerable effect that we cannot fail to see, and then we say that the effect is due to chance.

In this quote, Henri Poincaré explores the idea that small causes, often overlooked or unnoticed, can lead to significant effects. He suggests that when these effects become apparent, we tend to attribute them to chance, as if the outcome were purely random. Poincaré is pointing out the human tendency to simplify complex occurrences by labeling them as chance, even though they may have been set in motion by minor factors that we did not recognize at the time.

The meaning behind the quote speaks to the complexity of cause and effect in life and nature. Poincaré is highlighting how we often fail to trace back the origin of events to their subtle causes. By focusing only on the end result, we miss the intricate web of factors that lead to that outcome, and in doing so, we mistakenly attribute it to something as ambiguous as chance.

The origin of the quote lies in Poincaré's work as a mathematician and physicist, particularly in his studies of chaos theory and deterministic systems. His insights into how small changes can have disproportionate and unpredictable effects on a system are foundational to chaos theory. This quote reflects his broader philosophy that the universe operates in ways that might seem random but are actually governed by complex, often invisible, laws.

Ultimately, Poincaré’s words encourage a deeper reflection on the nature of chance and determinism. The quote suggests that what we perceive as random may simply be the result of hidden causes that we fail to recognize, urging us to consider the broader context and forces at play in any situation.