17. From the aforesaid discussion, it follows that amongst the various grounds on which parole can be granted, the most important ground, which stands out, is that a prisoner should be allowed to maintain family and social ties. For this purpose, he has to come out for some time so that he is able to maintain his family and social contact. This reason finds justification in one of the objectives behind sentence and punishment, namely, reformation of the convict. The theory of criminology, which is largely accepted, underlines that the main objectives which a State intends to achieve by punishing the culprit are: deterrence, prevention, retribution and reformation. When we recognise reformation as one of the objectives, it provides justification for letting of even the life convicts for short periods, on parole, in order to afford opportunities to such convicts not only to solve their personal and family problems but also to maintain their links with the society. Another objective which this theory underlines is that even such convicts have right to breathe fresh air, albeit for (sic short) periods. These gestures on the part of the State, along with other measures, go a long way for redemption and rehabilitation of such prisoners. They are ultimately aimed for the good of the society and, therefore, are in public interest.