What's the meaning of 'lips of' in this sentence?

Question

I encountered the following sentence while reading a book:

We soon discovered that many slips are possible between the cup of a promising idea and the lips of real-life applications, and that only a thorough understanding of these intermediate steps can turn a promising idea into something really useful and practical.

I can figure out the meaning from the context:

There might be many dangers between ideas and applications of the ideas. So the idea alone is not enough.

But I cannot figure out what the 'lips of' means there.

Answer 1

The quoted phrase is just a modern allusion to the aphorism, “There's many a slip 'twixt the cup and the lip“. The literal meaning is: though You might mean or plan to take a drink from a cup, completing the task without spillage is never certain until after the task is complete. This is synonymous to the idiom, “Don’t count your chickens before they hatch”