Introduction:
When it comes to revising Economics Optional for UPSC, it is important to have a systematic approach. There are two possible ways to revise the topics - in chronological order or by difficulty level. Let's analyze both approaches and understand which one would be more effective.

Revising in Chronological Order:
Revising Economics Optional in a chronological order of topics can be beneficial in several ways:

1. Conceptual Understanding: Following a chronological order allows you to grasp the subject's evolution and understand the development of economic theories over time. This approach helps build a strong conceptual foundation, as you can see how various ideas have evolved and influenced each other.

2. Logical Progression: Studying topics in a chronological order ensures a logical progression of ideas. This approach enables you to connect the dots and understand how different theories and concepts relate to each other. It helps in building a comprehensive understanding of the subject.

3. Exam Relevance: UPSC exams often require candidates to have a holistic understanding of economics. By revising in a chronological order, you can cover the topics that are more likely to be asked in the exam. For example, topics like Classical Economics, Keynesian Economics, and contemporary economic issues are frequently tested.

Revising by Difficulty:
On the other hand, revising by difficulty can also have its advantages:

1. Time Management: If you are short on time, revising by difficulty can help you prioritize topics that are more challenging. By focusing on difficult topics first, you can allocate more time to understand and revise them thoroughly.

2. Efficient Learning: Tackling difficult topics at the beginning helps you overcome any initial hurdles and build confidence. Once you have a solid understanding of complex concepts, revising easier topics becomes comparatively easier and quicker.

3. Targeted Preparation: By revising by difficulty, you can identify your weak areas and allocate more time to them. This approach allows you to focus on specific topics or concepts that require more attention, ultimately leading to better preparation.

Conclusion:
Both approaches have their merits, and the choice depends on your personal preferences and time availability. If you have ample time for revision, following a chronological order can provide a more comprehensive understanding of the subject. However, if time is a constraint, revising by difficulty can help you manage your time effectively and prioritize topics accordingly. Ultimately, it is essential to strike a balance between these two approaches and tailor your revision strategy to suit your needs and preferences.