  The mass of the central black hole in Seyfert galaxies and QSOs can be
determined from the broad emission lines and the reverberation method. Using
the measured black hole mass and the bolometric or ionizing luminosity, the
accretion rate can be estimated. Compiling a sample of Seyfert 1 galaxies and
QSOs with reliable central masses, estimated ionizing luminosities and X-ray
spectral slopes, we find that the X-ray spectral slope strongly correlates with
the accretion rate. The objects in the sample are found to be distributed in
two distinct classes in the spectral index versus Log(L_ion/L_Edd) plane. We
argue that these two classes may correspond to ADAF and thin disk accretion.
The observations of a ``two-state'' Seyfert 1 galaxy, 1H0419-577, confirm our
results. Detailed fitting of the spectra of individual Seyfert 1 galaxies and
QSOs using ADAF and/or thin disk models should further clarify the two-class
classification.
