"Hence no force, however great, can stretch a cord, however fine, into a horizontal line which is accurately straight: there will always be a bending downwards"

This quote by William Whewell is an allegory for the constraints of human power and stamina. It suggests that despite how effective or solid a person is, they can not attain excellence. Even if they try to extend a cord into a completely straight line, there will always be a slight bend or curve. This is a pointer that despite exactly how hard we attempt, we will never ever have the ability to achieve excellence. It is a pointer that we need to accept our limitations as well as pursue quality as opposed to perfection. The quote likewise serves as a reminder that we should not be too tough on ourselves when we make mistakes or fall short to accomplish our objectives. We ought to instead focus on gaining from our mistakes as well as aiming to do much better in the future.