Dear Balasubramaniam,
The replies of the above two learned friends inspire me also to join the discussion.
So far as I am able to understand, in general, discipline is an individual's state of mind reflected through his/her conduct in the social setup within which he/she lives. In other words, it is doing only what is prescribed as well as refraining from doing what is prohibited. That's how the rule of law takes precedence in the system of the administration of justice.
Applying the same analogy to employment, discipline is the predetermined set of values to be reflected in the behavior of the employees of an organization as its members.
Therefore, basically, discipline is the positive aspect of employment, and every employee is expected to observe the rules of discipline on their own. However, since no one is infallible at all times, the need to lay down the rules of discipline and the consequences of their transgression becomes inevitable. At the same time, as the zone of employment occupies only a limited space in an employee's life, the employer cannot engage in moral policing all the time. Hence the necessity for defining misconduct, its classification, and the negative consequences to be faced arises in the realm of employment. That's one of the objectives behind the framing of service regulations or the laws like the Industrial Employment (Standing Orders) Act, 1946, as the case may be.
At the same time, it is irrefutable that disciplining employees has its own negative connotations. Thus enters the application of the Principles of Natural Justice to the act of disciplining misconduct.
Excess of enthusiasm, at times, becomes an inherent aspect of power to control in tune with the saying "Power corrupts man and absolute power corrupts absolutely." That's where the concept of proportionality of punishment to the gravity of misconduct comes into play in disciplinary proceedings. It is always important that what is punished as a deterrent is only the act of misconduct and not the individual.