Why Is There the Merit of Samādhi When There Is Dhyāna?

Question: Why does meditative concentration (samādhi) bring the merit of concentration? 

Answer: Meditative concentration is divided into the concentration of the desire realm, the concentration of the form realm, and the concentration of the formless realm. The mind respectively corresponds to the states of the desire-realm heavens, the form-realm heavens, and the formless-realm heavens; after death, one will be reborn in the desire realm, the form realm, or the formless realm heavens, becoming a heavenly being, enjoying the supreme retributions of the heavenly realms, abiding in the corresponding meditative concentration and experiencing bliss. Therefore, concentration has the merit of concentration. The merit of concentration is worldly merit—the merit enjoyed within the world, the merit enjoyed within the world of the three realms.
Concentration represents purity, and purity is merit. Many people wish to be pure but cannot attain purity, which shows they lack the merit of purity. Concentration can make the body and mind comfortable and at ease, so concentration has the merit of concentration. Concentration can subdue and eliminate afflictions; without afflictions, the mind attains liberation, so concentration has the merit of concentration. Concentration can give rise to wisdom, so concentration has the merit of concentration. Concentration can dispel distracting thoughts and miscellaneous affairs, remove disturbances, and allow one to enjoy a wonderful time of pure happiness, so concentration has the merit of concentration. Concentration can give rise to immeasurable supernatural powers and spiritual abilities, can initiate vast and supreme practices, can benefit oneself and benefit others, can accomplish all worldly and transcendent endeavors, and can accomplish all worldly and transcendent wisdom; therefore, concentration has the merit of concentration. 

Concentration can avert disasters. For example, in the fourth dhyāna, where one abandons thought and attains purity, the three disasters cannot reach it; therefore, concentration has the merit of concentration. As long as there are mental thoughts, disasters can be attracted; great karmic activities, especially those accompanied by afflictions, bring even greater disasters. When the mind is pure and discards thoughts and imaginings, without desires and without seeking, one will not attract disasters. However, the fourth dhyāna is not ultimate either. After the meditative concentration dissipates, feelings of suffering will appear. Every kind of meditative concentration is subject to arising and ceasing; without realizing the fruits, without seeing the mind, and without cultivating to a considerably high level of wisdom, meditative concentration will eventually dissipate, and after it dissipates, afflictions and disasters will appear. The merit of concentration without having seen the Path is tainted merit; once the merit is enjoyed to its end, it will be completely exhausted. Therefore, one should still pursue the liberating wisdom born from meditative concentration—this is the supreme retribution that endures forever.