An Unexpected Poem

G & I took a stroll around Stowe gardens today where there's always a lot to photograph.  We found a route behind one of the follies and found this poem written out in stones on an old window ledge.  I googled it when I got home and it seems to be an extract from The Vigil of Venus, a poem in Latin attributed to Tiberianus, which is thought to date from the 4th century.  

There appear to be different English translations, I chose this one:

Let those love now who never loved before,
Let those who always lov'd, now love the more.