The Perfection of Energy - Effort or endeavour for kusala

The cetasika viriya, energy, accompanies almost all cittas, except sixteen ahetuka cittas, cittas that are unaccompanied by beautiful roots or unwholesome roots. Thus, whenever attachment and delight with regard to an object arises, the cetasika of energy accompanies that citta and performs its function of effort or energy for attachment and delight in that object. Be it akusala citta or kusala citta which arises, viriya cetasika accompanies that citta. When akusala citta arises, viriya cetasika is effort for akusala, whereas when kusala citta arises, viriya  cetasika performs its function of effort for kusala. The perfection of energy is effort or endeavour for kusala.
There should be energy or effort for each kind of kusala and when developed, it can become the perfection of energy. When sati arises and is aware of the characteristics of realities that are appearing at this moment, there is not me or self who makes an effort to be aware, but it is the function of right effort, samma- vayama. Right effort, viriya cetasika, arises and endeavours to study with awareness, to notice and pay attention to the reality that is appearing. Right effort is effort or energy for panna which understands that what appears through the eyes is only a kind of rupa which does not last; or that the reality which is seeing is only an element, a characteristic of nama-dhamma experiencing what appears through the eyes. This is the perfection of energy that endeavours to study the characteristics of realities appearing one at a time. It does not matter whether the perfection of energy arising with satipatthana occurs often or seldom, viriya is not weary of the task of studying and noticing the reality that appears. When viriya arises, we are not discouraged; viriya is always performing its task even if the process of development of understanding is extremely slow and difficult.