Principia: One Equation a Day

The universe of equations. In your pocket. Principia reveals one equation each day and connects it to the world around you. Discover the ideas behind music, markets, living systems, information, light, motion, and the cosmos. Press and hold to reveal the day's equation. Then explore it in clear, thoughtful layers: what it means, how its symbols work, how the idea emerged, where it appears in the real world, and why it matters. This is not a textbook. It is a daily ritual for curiosity. A DAILY RITUAL • One focused idea each day, with no feed and no endless scrolling • Beautifully typeset equations with plain-language explanations • History, real-world uses, and surprising connections • An optional one-question quiz after each full reveal • Curated, Foundational, Curious, and Advanced difficulty preferences MAKE IT YOURS • Build a daily streak, with one grace day for an isolated miss in each streak run • Explore your activity heatmap and celebrate milestones • Create beautiful share cards for revealed equations and milestones • Add Home Screen and Lock Screen widgets • Choose gentle reminders scheduled locally on your iPhone PRIVATE, ACCESSIBLE, AND READY OFFLINE • No Principia account, advertising, analytics, or tracking • Progress stays on your device, with private iCloud sync for selected progress • Feedback is sent only when you choose • Designed for VoiceOver, with a hand-authored spoken reading for every equation • Core learning content and math rendering work offline after install PRINCIPIA PRO Your first two full reveals include the complete story and quiz at no charge. After that, the daily equation, summary, Why It Matters section, and sharing remain free. Principia Pro unlocks: • The full story and optional quiz for each new daily equation • Your growing Library of revealed equations, with search, favorites, and themed collections Choose Principia Pro Monthly, Principia Pro Annual, or a one-time Principia Pro Lifetime purchase. A 7-day introductory trial may be available with the Annual plan for eligible new subscribers. Current localized pricing and trial eligibility appear before purchase. Payment is charged to your Apple Account when you confirm a purchase. Subscriptions renew automatically unless canceled at least 24 hours before the end of the current period. Your account is charged for renewal within 24 hours before the period ends. You can manage or cancel subscriptions in your Apple Account settings. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://joinprincipia.netlify.app/privacy Carry a universe of equations in your pocket. One Beautiful Equation a Day.