The large and the small of interstellar dust - Commentary on: Désert F.-X., Boulanger F., and Puget J.-L., 1990, A&A, 237, 215A. G. G. M. TielensA&A, 500 1 (2009) 335-336DOI: https://doi.org/10.1051/0004-6361/200912167