The character 思 sī, to think, is formed by, 心 xīn, heart and 田 tián, field. Bizarre? Yes and no. For aesthetic reasons or convenience or for fluidity in writing with the brush, some characters have lost a line, a dot, or have even given way to others. Let’s go back to the origin of 思 :
An ancient writing includes the heart at the bottom and the brain:
Articles on Chinese characters, by radical :
29 July 2020