The heart knoweth its own bitterness; literally, the heart (leb) knoweth the bitterness of his soul (nephesh). Neither our joys nor our sorrows can be wholly shared with another; no person stands in such intimate relation to us, or can put himself so entirely in our place, as to feel that which we feel.
There is many a dark spot, many a grief, of which our best friend knows nothing; the skeleton is locked in the cupboard, and no one has the key but ourselves. But we can turn with confidence to the God-Man, Jesus, who knows our frame, who wept human tears, and bore our sorrows, and was in all points tempted like as we are, and who has taken his human experience with him into heaven.
A stranger doth not intermeddle with its joy. The contrast is between the heart's sorrow and its joy; both alike in their entirety are beyond the ken of strangers. St. Gregory remarks on this passage ('Moral.
,' 6.23), "The human mind 'knoweth its own soul's bitterness' when, inflamed with aspirations after the eternal land, it learns by weeping the sorrowfulness of its pilgrimage. But 'the stranger doth not intermeddle with his joy,' in that he, that is now a stranger to the grief of compunction, is not then a partaker in the joy of consolation."
A homely proverb says, "No one knows where the shoe pinches so well as he that wears it;" and an Italian maxim runs, "Ad ognuno par piu grave la croce sua"—"To every one his own cross seems heaviest."
Septuagint, "The heart of man is sensitive ( αἰσθητική), his soul is sorrowful; but when it rejoices, it has no intermingling of insolence;" i.e. when a man's mind is sensitive it is easily depressed by grief; but when it is elated by joy, it should receive its pleasure and relief without arrogance and ribaldry.