The line "Let the knives be sharp and clean" evokes the image of someone preparing to use knives for a task that requires precision and care. The use of the word "sharp" implies that the knives will be effective in their purpose, while the word "clean" suggests that the knives are free from any dirt or debris that might compromise their function. Overall, this line creates a sense of readiness and attentiveness, as if someone is taking care to ensure that everything is in order before beginning a task that requires skill and focus.