وغاية علم الميزان الإصابة في الفكر وحفظ الرأي عن الخطأ في النظر
The aim of the science of the balance is correctness in thought and safeguarding judgment against error in reasoning.
Correctness in thought means reaching a sought conclusion through appropriate reasoning. Safeguarding judgment describes the benefit of avoiding invalid inference.
The aim is not achieved simply by reading a book. It requires understanding the rules, choosing appropriate premises and applying those rules. Thus “observance” in the definition and “protection from error” in the aim are closely connected.