Even a hardened cage is always a prison for the bird

The advice suggests that when we accept living conditions that are too comfortable, we should be mindful of the potential cost we may have to pay. The metaphor of the bird in the golden cage implies that the bird has lost its freedom and ability to move about and live life fully, despite being in a luxurious and comfortable environment.

In other words, the advice cautions us to be wary of situations that seem too good to be true, because they may come with strings attached. It reminds us to not be blinded by short-term pleasure or luxury and to consider the long-term consequences of our decisions.