this  -- "This" is translated from a Greek adjective that means "this," "that," "the nearer." Without a noun, it has the sense of "this one" or "that one." It is in the form of a subject.

is -- The verb "is" here is the common form of "to be" in Greek. It means to have a certain characteristic or remain in a certain condition. It also equates terms or assigns characteristics.

the -- The word translated as "the" is the Greek definite article, without a noun, it has the sense of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those") than the English "the." See this article for more. 

bread -- The word translated as "bread" means "small loaf or cake of bread." It is more like a slice of bread today. It describes a thin 1/2 inch thick round or an oblong loaf of wheat bread, meant to be torn into pieces and not cut. It was closer to a flour tortilla or a piece of pan than a loaf of bread.

which -- (CW) The word translated as "which" is the Greek definite article, without a noun, it has the sense of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those") than the English "the." See this article for more.

cometh -- (WF) -- The verb translated as "comes down" means "go down," but root word means "steps" so, with the prefix, the sense is "steps down," which I find more poetic. When speaking of the sky, we say in English that things "come down" not "go down." This form here is not an active verb but a participle, "stepping down."

down  - The "down" is from the prefix of the verb that means "down."

from -- The Greek preposition translated as "from" means "out of" or "from."

missing "the"  -- (MW) The untranslated word is the Greek definite article, which usually precedes a noun and, without a noun, takes the meaning of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those"). See this article for more. 

heaven, -- The word translated as "heaven" means "sky," the "climate," and the "universe." It also meant the home of the gods in a physical sense: the sun, moon, and planets were named for the gods. More about the word in this article.

that -- The word translated as "that" is an adverb "in that place," "there," "where," "when," or as a conjunction that starts a subordinate clause  "that," "when," "in order that" or "because."

a -- There is no indefinite article in Greek, but when a word doesn't have a definite article, the indefinite article can be added in English translation.

man --  (WW) The Greek word translated as "man" in the singular means "anyone," "someone,"  "something," and "anything." In the plural, it means "some," "they," and "those."  This is not the word for "man."

may -- This helping verb "may" indicates that the verb indicates a possibility, the subjunctive. Helping or auxiliary verbs are needed to translate the Greek verb forms into English.

eat -- The word translated as "ye shall eat" means "eat" but it also means "fret," as we say "something is eating me up."

there- -- The word translated as "there" is the Greek word commonly translated as third-person pronouns in English.

of, -- The Greek preposition translated as "of" means "out of" or "from." In Greek, they use the genitive case instead of a preposition for the types of phrases the "of" phrases.

and -- The Greek word translated as "and" is used as the conjunction "and," but it also is used to add emphasis ("also"). In a series, it is can be translated as "not only...but also." After words implying sameness "as."

not -- The negative used here is the Greek negative of a subjective opinion, commands, and requests. The sense is that "you don't want" or "think" something, not that it isn't done or thought. When a negative precedes the verb, it affects the whole clause.  It is the negative used with verbs of possibility, actions that "might" or "should" happen because that is an opinion. That is why it is used here.

missing "should" or "might"-- (MW) A helping verb is necessary because the following verb is a verb of possibility, a subjunctive, something that "should" or "might" occur. The helping verb is not needed in a clause beginning with an "if" or a "when."

die. - "Die" is a Greek verb that means "to die" and "to die off." Since the root word also means "to die," and the prefix means "away," the sense is to "die away" or to "die off."