Luk 5:13 I will: be thou clean.
I want to. Let yourself be purified!
Before this quote, someone with a skin disease recognizes that Christ has the power to "cleanse" him ( Luk 5:12). The word translated as "leper" simply means "the rough" and refers to anyone with any skin disease.
The Greek word translated as "will" means "to consent" and "to be resolved to a purpose". The English phrase "I will" is easy to confuse with an indication of doing something in the future because that is how "will" is commonly used in English. But in Greek, Christ is not saying that he is going to be doing something in the future. The Greek word does not work the same as the helper verb "will" in English. Its primary purpose is to express consent and even a delight in doing something. It doesn't even mean "desiring" or "wanting" to do something. It means "I consent" or "I resolve to do so."
The Greek word translated as "be clean," means to remove dirt. It is a passive command. It is used for a lot of specific types of "cleaning" including cleansing a person of leprosy but it also has a general meaning of "purifying" anything. It is in the form of a command. Both the leper and readers today are told to become pure of contaminants.
A general meaning of becoming pure and a specific meaning of being freed of leprosy.
Θέλω, (verb 1st sg pres ind act) "I will" is thelo, which as a verb means "to be willing (of consent rather than desire)", "to wish", "to ordain", "to decree", "to be resolved to a purpose" "to maintain", "to hold", "to delight in, and "will (too express a future event with inanimate objects)." As a participle, it means "being willing" or, adverbially, "willingly," and "gladly".
καθαρίσθητι: (verb 2nd sg aor imperat pass) "Be clean" is katharizo, which means "to clean", "to clear the ground of weeds,""prune away", "to remove dirt", "to purify,"and "to remove impurities." It is also used to describe the removal of the inedible parts from grain (winnowing), clearing weeds from a field, pruning a plant and so on.-- The Greek word translated as "be clean," means to remove dirt. It is used for a lot of specific types of "cleaning" including cleansing a person of leprosy but it also has a general meaning of "purifying" anything.