Think lightly on big matters. Think hard on small ones.

The source

"Think lightly on big matters. Think hard on small ones." Yamamoto Tsunetomo said it in Hagakure, Book 1. Translated from the original Japanese by Spartan Surfers.

"大事の思案は輕くすべし ... 小事の思案は重くすべし"

Original Japanese, Hagakure, Book 1. Japanese: Hagakure, vol. 1 (1937 printing), NDL digital text; Nabeshima Naoshige's wall maxim with Ittei's gloss, quoted in Hagakure.

Who said it

Yamamoto Tsunetomo (1659–1719). Samurai turned monk whose spoken reflections were written down as Hagakure, Hidden by Leaves.

Questions

Who said "Think lightly on big matters. Think hard on small ones."?

Yamamoto Tsunetomo (1659–1719). Source: Hagakure, Book 1.

What is the original Japanese?

大事の思案は輕くすべし ... 小事の思案は重くすべし. Translated from the original Japanese by Spartan Surfers.