I first heard about Rousham House and its gardens during a talk given by Monty Don at Hadlow College last year, although I now understand that at the time I’d missed the full import of what he was saying. My eager note taking records “Rauscham [sic], Grand house, William Kent (designer), Amazing rill”, and then moves on to record details of Jacques Wirtz’s garden. There is indeed an amazing rill at Rousham, and the knowledge of this together with supporting photographs later gleaned from the internet had so lodged in my head that I’ve been looking forward all year to visiting this miraculous water feature, and maybe even poking a toe in it. This became the reason for the visit and so, upon arrival on a beautiful hot and sunny September afternoon, I was impressed, but not overly moved, by the house, the park and the gardens. A crenellated eighteenth century stately home, with neat clipped box hedging and immaculate bowling green, complete with Cotswold stone-walled haha to prevent grazing animals wandering from the park land into the gardens. At the end of the bowling green, the view down to the winding Cherwell River below was certainly picturesque, but it wasn’t until we descended to the lower level via the cool woodland path on the left that it began to become apparent that this was more than a little out of the ordinary. Classically-themed statues and urns on plinths are revealed to the visitor, their aged stonework softened to a beautiful patina, and glades and vistas open out around corners. Where the site narrows a beautiful arched terrace provides views down across the grassy Venus’ Vale, with its pool and grottoes, towards the river, while functionally acting as a retaining wall to the bank supporting the highest path.
And we’d been wandering a while before it occured to us; there were no flowers to speak of in this garden - it’s a garden of green, and it works wonderfully. And revisiting my notes from Monty’s talk, I see that I did also write something about this, the “power of green”, and that even the white garden at Sissinghurst is really a green garden*. And a few lines on, I find a reference to Pope, who advises “consult the genius of the place”.
Consult the genius of the place in all;
That tells the waters or to rise, or fall;
Or helps th' ambitious hill the heav'ns to scale,
Or scoops in circling theatres the vale;
Calls in the country, catches opening glades,
Joins willing woods, and varies shades from shades,
Now breaks, or now directs, th' intending lines;
Paints as you plant, and, as you work, designs
Alexander Pope, from Epistle IV, to Richard Boyle, Earl of Burlington
And now, being on the cusp of understanding this, I can begin to hope to appreciate the rill in the context of the garden, not as a feature to be consumed. And not, thanks to Emma, by charging up it from its outlet at the Octagon Pool, but by seeking it out at its source, which must be approached from the vale by taking the lower, parallel path in the opposite direction, towards the statue of Apollo and the Temple of Echo in the glade beyond.
It was worth the wait. Emerging from a hole in the ground – through what means I have yet to find out (A spring? A pump? Some cunning hydraulics?) – a limestone channel winds its serpentine way beneath a wooded canopy. The rill arrives first at the octagonal Cold Bath – a deep, crystal looking glass reflecting the trees overhead and the adjacent grotto, and from there on between well tended hedges of laurel to the pool in the vale. This is surely a prodigious feat of engineering, and certainly a gentle, yet breathtaking spectacle. 
*with the exception of the flower spike on the Melianthus, which is a rusty red, even though Lex laughed at me and said it never flowers, which is odd, because mine does in north Kent less than an hour away.