We suggest a simple physical picture for the diffractive parton distributio
ns that appear in diffractive deeply inelastic scattering. In this picture,
partons impinging on the proton can have any transverse separation, but on
ly when the separation is small can they penetrate the proton without break
ing it up. By comparing the predictions from this picture with the diffract
ive data from DESY HERA, we determine rough values fur the small separation
s that dominate the diffraction process.