Why do Russians refer to flatterers as "downlickers" (подлизы)?

Question

Usually used to refer to a flatterer, the Russian word подлиза literally means a downlicker: the prefix под- means down, below, beneath, or under, and the root -лиз- is common to Russian words about licking (лизать, лизун, etc.), so the whole word can be literally understood as someone who licks from below.

I am curious as to exactly what process is a flattering compared to when the flatterer is referred to as подлиза. What is the flatterer figuratively implied to lick, or what was the underlying logic when this word came to existence?

I tried to find the answer on my own and did research on the Internet, but found only explanations of the morphological composition of подлиза, so I hope that native speakers can shed some light.

Answer 1

"Подлизывать" initially meant "лизанием подчищать что-либо". There's are some other words derived from "лизать" that used to be (and some still are) used as figurative terms for flattery-related concepts, such as:

• лизоблюд (and "лизоблюдство", also, more rare form "блюдолиз")
• жополиз (Радищев wrote once: "Не льстец Августов и не лизорук меценатов" - my guess would be that "лизорук" was his attempt to use less rude counterpart of "жополиз", pretty much like people are using "фиг" to avoid usage of obscene lexicon).

The underlying logic is to compare the flatterer with, say a dog, who keeps licking someone hoping to get a food.