The logographic nature of the Chinese writing system does not mean that Chinese characters are necessarily arbitrary symbols. In fact most recorded characters¹ contain a phonetic element that (originally at least) gives away the pronunciation of the word that it stands for. Characters that contain only semantically relevant elements are rare, en become even rarer beyond the basic vocabulary of Chinese.
In essence characters that contain more than one element are incredibly likely to contain an element that originally hinted at the pronunciation of the word the character stood for. Even characters that are traditionally analysed semantically, as for example 安 (with old meanings as ‘be calm, peaceful, still, steady, take one's leisure’), where the ideographic analysis ‘a woman under the roof’ somehow should give away the word, turn out upon closer inspection to be analysable as a combination of a phonetic element and a semantic element anyway.² However, often the ancient scribes that created the characters seem to have tried to come up with phonetic elements that had a semantically relevant aspect as well³ and if knowledge of the phonetic is lost (for example through changes in the spoken language) the semantic values are all that remains.
For example, in the case of 盥 it's really hard to identify any element as a phonetic, while its really easy to see that it is composed of 皿 (a dish) 水 (water) and symbols for hands (left and right), implying that it's meaning has to do with ‘washing one's hands’ - which is indeed its primary meaning in Chinese.⁴
Having said that, a lay person is unlikely to recognise any of the elements (dish, hands, water) even though they all have a pictographic origin. It is perhaps a bit like a formula of which you don’t know the meanings of the symbols.
1. According to some wikipedian this group of characters could make up 90% of all characters. While that may be true, the frequency of usage of some of the simple, originally pictographic or only semantic characters is relatively high, making those relatively well known. But yes, in absolute numbers close to all characters are of this ‘semantic-phonetic’ type.
2. According to Boltz (pp. 106-108) the phonetic element is 女 - which at some early stage was a polyphone, and was used to write two different words - which means it could be pronounced in two ways as well. Boltz isolates the lost pronunciation via the pronunciation that 安 妟 奻 姦 have in common; all belonged to the 元 yuan rime group. (William G. Boltz (1994) The origin and early development of the Chinese writing system. American oriental society: New Haven).
3. See Kenneth G. Henshall (1990) A guide to remembering Japanese characters. Tuttle: Tokyo.
4. Note that being able to pin down the general meaning of a Chinese character does not necessarily help you to identify the word it stands for. First, you have to know Chinese for ‘washing’. Second, there may be more than one word for washing. Also, modern Chinese has a preference for two syllable words. In modern Chinese 盥 will mostly be part of a compound word, like for example guànxǐ 盥洗 ‘wash up’.
