NOTE: if the celery is a little limp, cut the tops and bottoms of the stalks and let soak in some water to "refresh".
Thinly slice the celery. Chop the cilantro. Dice the peaches.
Put celery, walnuts, feta and cilantro in a bowl - and KEEP PEACHES SEPARATE. Gently mix together, and drizzle with about 8 T of olive oil and juice of 1 lemon. Add S&P to taste.
Serve -- with peaches to mix in for those that want them.