[523] Therein, what is energy (vīriya)?
That arousing of energy (vīriyārambha) which is mental (cetasika), … right effort (sammāvāyāma), the energy factor of awakening (vīriya-sambojjhaṅga), a factor of the path (magga), included in the path — this is called energy.
Therein, what is concentration (samādhi)?
That which is stability of the mind (citta), … right concentration (sammāsamādhi), the concentration factor of awakening (samādhi-sambojjhaṅga), a factor of the path, included in the path — this is called concentration.
Therein, what is the volitional formation of striving (padhāna-saṅkhāra)?
That arousing of energy which is mental, … right effort, the energy factor of awakening, a factor of the path, included in the path — this is called the volitional formation of striving.
Thus with this energy, with this concentration, and with this volitional formation of striving he is possessed, … endowed. Therefore it is said: "endowed with energy, concentration, and the volitional formation of striving."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.