By Patricia Kingswell 1:24 pm PST

Leonardo Da Vinci would grasp his small notebook that always hang from his belt and sketch profusely, whenever he came across something eye catching, says historian Toby Lester.

Da Vinci’s collection of notebooks are filled to the brim with sketches, measurements and observations, centred around four themes – painting, architecture, mechanics, and human anatomy.

“It is useful” he once wrote, “to constantly observe, note, and consider.”

Like many classical artists, Da Vinci clearly had a great passion for his artistry. He observed with great vigour, the natural world around him. You would find him immersed in the flight of birds, for example, to discover aeronautical principles.

Da Vinci was a sensual, spiritual, realistic, and mathematical man; all in one – an artist and an inventor.

He loved discovering the patterns and symmetries in nature, and learning mathematical calculations and measurements for proportion that allowed him to make sense of those discoveries.

Da Vinci discovered through drawing, and in turn, drew what he discovered. He had that insatiable appetite and obsessive passion that created many a genius.

As a painter, inventor, engineer, and scientist, he created 13,000 pages of notes to capture his creativity.

Buried deep within one of these books, dating back to around the 1490s, is a to-do list.

It reads:

[Calculate] the measurement of Milan and Suburbs

[Find] a book that treats of Milan and its churches, which is to be had at the stationer’s on the way to Cordusio

[Discover] the measurement of Corte Vecchio (the courtyard in the duke’s palace).

[Discover] the measurement of the castello (the duke’s palace itself)

Get the master of arithmetic to show you how to square a triangle.

Get Messer Fazio (a professor of medicine and law in Pavia) to show you about proportion.

Get the Brera Friar (at the Benedictine Monastery to Milan) to show you De Ponderibus (a medieval text on mechanics)

[Talk to] Giannino, the Bombardier, re. the means by which the tower of Ferrara is walled without loopholes (no one really knows what Da Vinci meant by this)

Ask Benedetto Potinari (A Florentine Merchant) by what means they go on ice in Flanders

Draw Milan

Ask Maestro Antonio how mortars are positioned on bastions by day or night.

[Examine] the Crossbow of Mastro Giannetto

Find a master of hydraulics and get him to tell you how to repair a lock, canal and mill in the Lombard manner

[Ask about] the measurement of the sun promised me by Maestro Giovanni Francese

Try to get Vitolone (the medieval author of a text on optics), which is in the Library at Pavia, which deals with the mathematic.

[Wendy MacNaughton for NPR]

Da Vinci constantly tried to push beyond his limits. He thrived in the rise of the European Renaissance, when art and science were intertwined.

By reaching out and soaking in the universe around him, Da Vinci was able to express himself through his visionary work.

He lived life based on a philosophy that there were no limits to one’s capacity for development and expansion, and with a goal to reach his fullest potential.

“…stagnant water loses its purity and in cold weather becomes frozen; even so does inaction sap the vigor of the mind. So we must stretch ourselves to the very limits of human possibility. Anything less is a sin against both God and man.”