A walled garden 
is designed to protect against wind and frost. A place that is protected. Safe.
A place where an intentional microclimate can be created, one that supports the organic growth of the plants inside. A place where plants can thrive in an environment that would normally kill them.
A place which has, at its center a wellhead or pool, inspired by the gardens of Persia and the mythology of Zoroaster. A wellspring.
A place of the imagination that inspires our collective imagination. Eden. Paradise.
>As the word expresses, such gardens would have been enclosed. The garden's purpose was, and is, to provide a place for protected relaxation in a variety of manners: spiritual, and leisurely (such as meetings with friends), essentially a paradise on earth.
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The Common Iranian word for "enclosed space" was *pari-daiza- (Avestan pairi-daēza-), a term that was adopted by Christian mythology to describe the garden of Eden or Paradise on earth. wikipedia
When Ward set about to Reimagine the wiki, he did so to encourage the emergence of gardens of meaning. Personal gardens, each which had walls of safety.
While someone can freely borrow from your thoughts, they cannot overwrite your thoughts.
He found that, as the original wiki aged, much of his time was spent cleaning out malicious overwriting. So much so, he finally locked the doors to that garden.
As he reimagined, he sought to create a new experience, one that allowed others to wander freely and build paths of connections between personal gardens - all supporting and celebrating divergent thought. Not convergent thought, that which manifested in the original wiki design as it became a platform for knowledge-bases such as Wikipedia.
It is when our paths intersect that we have the tension of orthogonal thought in an Ecotone that invites reflection and leads us to new insight.
New creations of our genius, our innate spirit, that is life-giving.