不为人知

不 = 丆 + 卜 : Bruno Bear (bu) is setting up a wind wheel (丆) with a voodoo staff (卜) in the space station's bathroom (Ø4). He also puts a "forbidden" sign (mnemonic symbol for 不) on it, to make clear that it may not (不) be stopped.

为 = ⺀ + 力 : This one looks like a bird with crazy hair, and when I googled "bird with crazy hair", wow was I amazed how many birds with crazy hair there are! Penguins are birds with crazy hair! So let's use a penguin for this character.

为 = ⺀ + 力 : The crazy hair penguin wants to use the Eiffel Tower's bathroom, but because Willy Walrus just finished it stinks like hell. The first thing crazy hair penguin does is to press the button to release a heap of blossoms to make the air breathable again.

人 = 丿 + ㇏ : Mnemonic symbol: Neanderthal Man (人). Robinson Crusoe (r-) is looking for snacks in the encampment's kitchen (-en2) when he suddenly spots Neanderthal Man (人). Neanderthal Man offers him a banana (丿), but Robinson Crusoe doesn't trust the present and pokes it with a finger (㇏).

知 = 口 + 矢 : Mnemonic symbol: Francis Bacon is attributed to have stated "scientia potentia est", "knowledge is power". I'll thus represent 知 by Francis Bacon. Francis Bacon (知) and James II of England (zh) are playing darts (矢) in front of the space station (Ø1). Because they lack a dart board they just use a mandarin (口).