Gustave Flaubert wrote that "an infinity of passion can be contained in one minute." So, if you have boundless passion for contemplating the immeasurable, a full day should offer plenty of time. August 8 (8/8) is Infinity Day since the numeral 8 looks like a tilted ∞, the common symbol for infinity first popularized in 17th-century math books. But the concept of infinity itself represents an idea much older, inherent in the countless spiritual traditions that revere eternal gods or outline endless life cycles.