It's quite possible that the purpose of the ditch was to provide soil for the bank! Once you defined your 'sacred goat enclosure' on the ground you wouldn't want to pile the soil up inside it would you :-)

Fill 'em with water and create an island inside. Myths are full of legends of far away magical islands. Could they have been the structures currently known as henges? Or could the henge be a representatin of such a place?

>For that reason, I believe that the key to opening up the truth of the purpose of henges lies in the function of the ditch.<

Think you've put your finger on it although, as FourWinds says -

>It's quite possible that the purpose of the ditch was to provide soil for the bank!<

In which case it's more the bank than the ditch that's the key.

So perhaps we're back to the question of the bank - ie <i>Which side of the ditch is the spoil from the ditch deposited?</i> If the spoil is on the <i>inside</i> of the ditch that would seem to indicate a defensive structure. If the spoil is on the outside of the ditch that would seem to indicate a sacred, ceremonial or utilitarian (or a combination of all three) use for the structure.

My bet's on the latter.