“Pythagoras said that this world was like a stage,
Whereon many play their parts; the lookers-on, the sage
Philosophers are, saith he, whose part is to learn
The manners of all nations, and the good from the bad to discern.”

Source: A Natural History of the Senses (1990), Chapter 3 “Taste” (p. 131)

Jaques, Act II, scene vii.
Variant: All the world's a stage,
And all the men and women merely players:
They have their exits and their entrances;
And one man in his time plays many parts.
Source: As You Like It (1599–1600)

Hayek revisited (1993)

62 Eudæmonidas
Apophthegms of Kings and Great Commanders

Source: The Merchant of Venice

"It's written by Charles Grosvenor Osgood (1871-1964), as part of a 1917 preface to Boswell's 'Life of Johnson.'"
The Samuel Johnson Sound Bite Page http://www.samueljohnson.com/apocryph.html#2 Retrieved 2013-07-07
Misattributed

Source: Discourses (1967), Vol. I, Ch. 15 : The Life of the Spirit
Context: The value of material things depends upon the part they play in the life of the spirit. In themselves they are neither good nor bad. They become good or bad according to whether they help or hinder the manifestation of Divinity through matter. Take for example the place of the physical body in the life of the spirit. It is a mistake to set up an antithesis between “flesh” and “spirit.” Such contrast almost inevitably ends in an unqualified condemnation of the body. The body obstructs spiritual fulfillment only if it is pampered as having claims in its own right. Its proper function is rightly understood as ancillary to spiritual purposes. The rider needs a horse if he is to fight a battle, though the horse can become an impediment if it refuses to be completely submissive to his will. In the same way the spirit needs to be clothed in matter if it is to come into full possession of its own possibilities, although the body can at times become a hindrance if it refuses to be compliant with the requirements of the spirit. If the body yields to the claims of the spirit as it should, it is instrumental in bringing down the kingdom of heaven on earth. It becomes a vehicle for the release of divine life, and when it subserves this purpose it might aptly be called the temple of God on earth.

Source: A Fine Balance