Since citta are differentiated by jati as kusala, akusala, vipaka and kiriya, the cetasika that arise concurrently would be of the same jati as that citta.  Akusala-cetasika could not arise with kusala-citta, vipaka-citta or kiriya-citta.  Kusala-cetasika could not arise with akusala-citta, vipaka-citta or kiriya-citta.  Nor could vipaka-cetasika arise with akusala-citta, kusala-citta or kiriya-citta.  Therefore vedana-cetasika are also distinguished by being kusala, akusala, vipaka and kiriya like all other cetasika.  However, the Buddha did not manifest the characteristics of each reality in detail so there could be those who misunderstand the characteristics of vedana-cetasika such as physical dukkha-vedana, which are feelings of sickness, aches and pains, which arise with the kaya-vinnana-citta, the citta that knows bodysense contact, that arises just an instant of citta, unlike the feeling of domanassa (unpleasantness) when in contact with the physically unpleasant arammana.  Since each instant of citta differs in detail by the vedana-cetasika arising with it, the Buddha manifested precisely which vedana arises concurrently with a distinct kind of akusala-citta, kusala-citta, vipaka-citta and kiriya-citta. 

The instant there is pain there is dukkha-vedana through the bodysense which is akusala-vipaka, while the instant there is unhappiness, perturbation, and worry because of dukkha-vedana, there is no vipaka.  At that instant there is akusala-vedana arising with akusala-citta so there is unhappiness. 

 The conscientious study of the Abhidhamma would make us correctly understand the characteristics of vedana-cetasika that arise with the citta, or else one would be deceptively attached to somanassa-vedana, sukha-vedana or upekkha-vedana without recognizing which instant of vedana is kusala, which akusala, which vipaka or which is kiriya. 

 In the Anguttaranikaya Ekanipata Dutiyapannasaka Sanimitta the third vagga, 328, there is a passage saying: Behold, Bhikkhu, dhamma that is sinful akusala arises because there is vedana.  Without vedana, it does not arise. By abandoning the vedana the dhamma that is sinful akusala would no longer be. 

 (Other passages are about sanna-cetasika, which is the sanna-khandha, other cetasika that are sankhara-khandha and the citta which are vinnana-khandha.) 

 This shows that the vedana-cetasika, which are feelings, are the basis of tenacious attachments.  Since there is no knowledge of the truth about vedana-cetasika, one cannot abandon the feeling that there is oneself. 

 The knowledge of the characteristics of vedana-cetasika would condition and support sati to arise and know the characteristics of vedana.  Otherwise one would not realize that every day there is vedana in the same way that each day there are only realities that appear through the eyes, ears, nose, tongue, bodysense and mind, only because citta arise to know these realities.  But imagine if one does not feel anything, when one sees the world there would be no perturbation.  If one does not feel any emotion after hearing, one would not feel disturbed either.  And the same applies to smelling, tasting, knowing bodysense contact, there would be no akusala of any kind.  But because feelings arise, there is attachment and clinging to the feelings and desiring the objects that make us feel glad and happy, which cause akusala-dhamma to arise frequently without our awareness.  All dhamma are anatta and none can prevent vedana-cetasika from arising.  Whenever citta arises there must be vedana-cetasika that feels the arammana of the moment.  Even now there must be vedana-cetasika of one kind or another being upekkha-vedana, sukha-vedana, dukkha-vedana, somanassa-vedana or domanassa-vedana.  The aim of studying dhamma is not merely to know the number or names but the characteristics of the feelings one is having.  If sati does not arise to be conscious of the feelings that we are having now, even though that feeling is real: it has arisen and fallen away, since we do not know the true characteristics of that feeling, we would take it for the selves, which are happy, unhappy, glad, sad or indifferent. 

 Therefore as long as sati does not arise to be mindful of the characteristics of feelings or emotions, there is no way to abandon attachment to realities as entities, persons, or the selves, because each would cling to feelings as important factors of life.  Everyone desires pleasant emotions.  No one wants unhappy feelings.  Therefore no matter how, one would endeavor to make sukha-vedana or somanassa-vedana arise without realizing that in that instant there is attachment clinging to feelings that arise because of causes and then fall away.  Since feelings are important things to which all are attached, the Buddha manifested that the vedana-cetasika alone is the vedana-khandha because it is an important reality that is taken for the self, the entity, the person.  For the sati to arise and be conscious of the characteristics of the truly existing realities that appear, one must rely on studying and listening to more and more detailed accounts about realities, examine and prove them in daily life also.