Death is the ultimate boundary of human matters. [ Horace ]

Sleep hath its own world, a boundary between the things misnamed death and existence. [ Byron ]

The boundary of man is moderation. When once we pass that pale our guardian angel quits his charge of us. [ Feltham ]

It is indeed the boundary of life, beyond which we are not to pass; which the law of nature has pitched for a limit not to be exceeded. [ Montaigne ]

Does the man live who has not felt this spur to action, in a more or less generous spirit? Emulation lives so near to envy that it is sometimes difficult to establish the boundary-lines. [ Henry Giles ]

Heroes have gone out; quacks have come in; the reign of quacks has not ended with the nineteenth century. The sceptre is held with a firmer grasp; the empire has a wider boundary. We are all the slaves of quackery in one shape or another. Indeed, one portion of our being is always playing the successful quack to the other. [ Carlyle ]