Introduction:
The Directive Principles of State Policy (DPSP) are a set of guidelines or principles laid down in Part IV of the Indian Constitution. These principles act as a moral compass for the state and guide it in making laws and policies to promote the welfare of the people. The 42nd Amendment to the Constitution, also known as the Mini-Constitution, was enacted in 1976 during the period of the Emergency. It introduced several changes to the Constitution, including the addition of a new principle to the DPSP.

Explanation:
The principle that was added to the Directive Principles of State Policy by the 42nd Amendment to the Constitution is the "Participation of workers in the management of industries". This principle is mentioned under Article 43A of the Constitution.

Importance of worker participation:
Worker participation in the management of industries is an important aspect of industrial democracy. It provides a platform for workers to have a say in the decision-making process of the industries they work in. This principle ensures that the interests of workers are taken into consideration and that they are not merely treated as laborers but as stakeholders in the organization.

Key provisions:
The addition of the principle of worker participation in the management of industries brought about the following key provisions:

1. Workers' participation in the management of industries should be promoted by the state.
2. The state should take steps to ensure that workers are provided with opportunities for participation in the management of industries.
3. The state should promote the formation of co-operative societies in industries to facilitate worker participation.
4. The state should provide assistance and support to co-operative societies formed by workers.
5. The state should encourage the promotion of voluntary organizations that represent the interests of workers.

Objective:
The objective of adding this principle to the DPSP was to empower workers and ensure their active involvement in decision-making processes related to their employment and working conditions. It aimed to create a more democratic and participatory work environment.

Conclusion:
The addition of the principle of worker participation in the management of industries through the 42nd Amendment to the Constitution was a significant step towards promoting industrial democracy and ensuring the welfare of workers. This principle emphasizes the importance of giving workers a voice in the decisions that affect their lives and livelihoods. By actively involving workers in the management of industries, the state aims to create a more equitable and inclusive society.