What this hexagram is about
Wind and thunder lending each other force, the higher diminished to enrich the lower — the image of increase and gain. The one above who reduces himself to benefit others wins the people's hearts; to move toward the good when one sees it and to mend one's faults — this is the way to increase oneself.
The Judgment 卦辞
益，利有攸往，利涉大川。
It is favorable to have somewhere to go. It is favorable to cross the great river.
The Image 大象传
《象》曰：风雷，益；君子以见善则迁，有过则改。
Wind and thunder, increasing each other; so the noble person, seeing good, moves toward it, and having faults, mends them.
Commentary on the Lines 小象传
元吉无咎，下不厚事也。
Supreme good fortune, no fault — those below are not burdened with heavy tasks.
The Six Lines (hover over the figure above)
Six at the top莫益之，或击之，立心勿恒，凶。
None come to increase him, and some come, instead, to strike at him; his heart cannot hold to any constancy — grasping without end, never knowing where to stop — misfortune.
Nine in the fifth place有孚惠心，勿问元吉，有孚惠我德。
With a heart of sincerity and a will to benefit others, one need not ask further — the highest good fortune; and all under Heaven will repay it in good faith, mindful of one's kindness.
Nine in the fourth place中行，告公从，利用为依迁国。
Holding to the central way, one reports to the duke and is heeded; it is fitting, by this, to lean on the great current of events — to move the realm and settle the people.
Nine in the third place益之用凶事，无咎。有孚中行，告公用圭。
To put the means of increase to the relief of disaster and hardship — there is no fault. Keeping faith in the heart and holding to the central way, one reports to the duke bearing the jade scepter as a token of utmost sincerity.
Six in the second place或益之十朋之龟，弗克违，永贞吉。王用享于帝，吉。
One is given a great tortoise worth ten strings of cowries that cannot be refused; to hold long to the right brings good fortune. The sovereign, with this, makes reverent offering to the Lord on High — good fortune.
Initial Six利用为大作，元吉，无咎。
It is fitting to use it for great undertakings — the highest good fortune, and no fault: receiving benefit from above, one should rouse oneself to act.