The Perfection of Energy - The attendant of panna

Viriya cetasika is classified among the cetasikas which are the “particulars”, pakinnaka. These cetasikas arise with many cittas but not with all. The six particulars are: applied thinking (vitakka), sustained thinking (vicara), determination (adhimokkha), energy (viriya), enthusiasm or rapture (píti), and wish-to-do or zeal (chanda). Viriya cetasika arises time and again, it accompanies many cittas in daily life, except sixteen rootless cittas, (ahetuka cittas), and it is the only cetasika among the “particulars” which can become a perfection. When viriya which is energy for kusala has been further developed it becomes the perfection of energy, viriya. In that case, viriya is the attendant of panna and a condition for the realization of the four noble Truths.
Is viriya that arises now kusala or akusala? If it is akusala it is not a perfection. Viriya is among the particulars and thus it can accompany kusala citta or akusala citta, but most of the time it is likely to accompany the akusala citta which is rooted in lobha, attachment. Viriya accompanies akusala citta countless times, but instead of applying energy for akusala, we should endeavour to accumulate the perfection of energy, we should see its benefit.
We read in the “Expositor” (Book I, Part IV, I, 121) about viriya:

“... energy has exerting as characteristic,

strengthening the conascent dhammas as function,

and opposition to giving way (to discouragement) as manifestation.

It has been said: ‘He being agitated, makes a rational effort,’

hence it has a sense of urgency,

or the basic condition of making energy, as proximate cause.”

  We can see that energy arises at the moment of diligence, and that it is the opposite of being lazy. However, according to the Abhidhamma which explains in detail the cetasikas accompanying citta, viriya accompanies akusala citta even when we are lazy, and in that case viriya applies itself to laziness again and again. The Dhamma is very subtle and it should be considered in all details; for example, the characteristic, function, manifestation and proximate cause of realities should be studied and investigated.