"One swallow does not make a spring."
This proverb, "Una hirundo non facit ver," was written by the Roman writer and philosopher Aristotle in his book "Historia Animalium."
The proverb means that a single event or occurrence does not necessarily signify a trend or a lasting change. Just as the appearance of a single swallow does not guarantee the arrival of spring, a single positive event does not mean that everything is good or that things will stay that way.
The proverb was later translated into English and slightly modified, becoming "one swallow does not a summer make." The meaning remains the same: do not jump to conclusions or assume a complete change based on a single piece of evidence.