Butterflies are symbolic.
When some people see a butterfly lazily gliding through the air while walking to get their mail or maybe while doing some much needed landscaping, the only thing that might cross their mind is, "how pretty," and they go back to what was originally occupying their time.
Other people treat butterflies as a message from loved ones that have past like the popular folklore that seeing a flaming red cardinal or picking up a random penny on the ground is a special message letting you know you're on someone's mind in a different time and place.
Butterflies hold different meanings and folklore for different people and cultures throughout the ages. For instance*: