四
=
儿
+
囗
:
Mnemonic symbol: a four-leaved clover. Socrates (s) is working out in the bathroom of the space station (Ø4). He's lifting four (四) wooden boxes (囗), and wonders why they are so heavy. He doesn't know that inside one of the four boxes, the monkey king (儿) is hiding and secretly laughing at him - until the monkey king comes out and surprises Socrates with a four-leaved clover (四).
儿
=
丿
+
乚
:
Mnemonic symbol: "son" (儿) sounds similar to "Sun" like in "Sun Wu Kong", so it's gonna be represented by the monkey king. Albert Einstein (Ø-) and Sun Wu Kong (儿) are fighting in the space station's kitchen (-Ø2). Their weapons: Albert Einstein has a shovel (乚), and Sun Wu Kong has a banana (丿).
Four Great Yuan Dramatists, namely: Guan Hanqing 關漢卿|关汉卿[Guan1 Han4 qing1], Zheng Guangzu 鄭光祖|郑光祖[Zheng4 Guang1 zu3], Ma Zhiyuan 馬致遠|马致远[Ma3 Zhi4 yuan3] and Bai Pu 白樸|白朴[Bai2 Pu3]