A parallel to the higher teaching of the Gospels (compare John 6:27; Matthew 26:26).

Come, eat of my bread - Not only receive my instructions, but act according to my directions.
Drink of the wine - I have mingled - Enter into my counsels; be not contented with superficial knowledge on any subject, where any thing deeper may be attained. Go by the streams to the fountain head. Look into the principles on which they were formed; investigate their nature, examine their properties, acquaint thyself with their relations, connections, influences, and various uses. See the skill power, and goodness of God in their creation. And when thou hast learned all within thy reach, know that thou knowest but little of the manifold wisdom of God. Let what thou hast learned humble thee, by showing thee how very little thou dost know. Thou hast drunk of the provided wine; but that wine was mingled with water, for God will hide pride from man. He dwells only on the surface of religious and philosophical learning, who does not perceive and feel that he is yet but a child in knowledge; that he see through a glass darkly; that he perceives men like trees walking; and that there are lengths, breadths, depths, and heights, in the works and ways of God, which it will require an eternity to fathom. Here below the pure wine is mingled with water: but this is God's work. Yet there is enough; do not therefore be contented with a little. To this subject the words of the poet may be well applied: -
A little learning is a dangerous thing; Drink deep,
or taste not the Pierian spring:
For scanty draughts intoxicate the brain,
But drinking largely sobers us again.
Pope
Among the ancient Jews, Greek, and Romans, wine was rarely drank without being mingled with water; and among ancient writers we find several ordinances for this. Some direct three parts of water to one of wine; some five parts; and Pliny mentions some wines that required twenty waters: but the most common proportions appear to have been three parts of water to two of wine. But probably the יין מסך yayin masach, mingled wine, was wine mingled, not with water, to make it weaker; but with spices and other ingredients to make it stronger. The ingredients were honey, myrrh, mandragora, opium, and such like, which gave it not only an intoxicating but stupifying quality also. Perhaps the mixed wine here may mean wine of the strongest and best quality, that which was good to cheer and refresh the heart of man.
If we consider the mixed wine as meaning this strong wine, then the import of the metaphor will be, a thorough investigation of the works of God will invigorate the soul, strengthen all the mental powers, enlarge their capacity, and enable the mind to take the most exalted views of the wonders of God's skill manifested in the operations of his hand.

Come, eat of my (f) bread, and drink of the wine [which] I have mixed.
(f) By meat and drink is meant the word of God, and the ministration of the sacraments, by which God nourishes his servants in his house which is the Church.

Come, eat of my bread,.... Which stands for all the provisions of Christ's house; it designs the Gospel, which to a believer is more than his necessary food; and the ordinance of the supper, one of the symbols of which is bread; and more especially Christ himself, the bread of God, the living bread that came down from heaven, which is to be eaten by faith; and this only, for everything else is that which is not bread; and this daily, as the Israelites ate their manna; this is the believer's daily bread; and largely and freely, to which they are welcome by Christ; and with gladness and singleness of heart, joyfully and with sincerity;
and drink of the wine which I have mingled; of the love of Christ; or of the love of the Father, Son, and Spirit, which meet and mingle together: to "drink" of this is to partake of it by faith, and be persuaded of interest in it; this may be drank largely of, for there is enough, a river of it; and without danger, it is not intoxicating as wine, wherein is excess; and it may be had freely, without money and without price, Song 1:2.

The plur. of the address shows that the simple (inexperienced) and the devoid of understanding are regarded as essentially one and the same class of men. The בּ after לחם and שׁתה proceeds neither from the idea of eating into (hewing into) anything, nor from the eating with anything, i.e., inasmuch as one makes use of it, nor of pampering oneself with anything (as ראה ב); Michaelis at last makes a right decision (cf. Leviticus 22:11; Judges 13:16; Job 21:25, and particularly לחם בּ, Psalm 141:4): communicationem et participationem in re fruenda denotat; the lxx φάγετε τῶν ἐμῶν ἄρτων. The attributive מסכתּי stands with backward reference briefly for מסכתּיו. That Wisdom, Proverbs 9:2, offers flesh and wine, but here presents bread and wine, is no contradiction, which would lead us, with Hitzig, critically to reject Proverbs 9:4 and Proverbs 9:5 as spurious; לחם is the most common, all-comprehensive name for nourishment. Bertheau suitably compares Jahve's invitation, Isaiah 55:1, and that of Jesus, John 6:35.