  Estimates of the accretion rate in symbiotic recurrent novae (RNe) often fall
short of theoretical expectations by orders of magnitude. This apparent
discrepancy can be resolved if the accumulation of mass by the white dwarf (WD)
is highly sporadic, and most observations are performed during low states. Here
we use a reanalysis of archival data from the Digital Access to a Sky Century
@Harvard (DASCH) survey to argue that the most recent nova eruption in
symbiotic RN T CrB, in 1946, occurred during -- and was therefore triggered by
-- a transient accretion high state. Based on similarities in the optical light
curve around 1946 and the time of the prior eruption, in 1866, we suggest that
the WD in T CrB accumulates most of the fuel needed to ignite the thermonuclear
runaways (TNRs) during accretion high states. A natural origin for such states
is dwarf-nova like accretion-disk instabilities, which are expected in the
presumably large disks in symbiotic binaries. The timing of the TNRs in
symbiotic RNe could thus be set by the stability properties of their accretion
disks. T CrB is in the midst of an accretion high state like the ones we posit
led to the past two nova eruptions. Combined with the approach of the time at
which a TNR would be expected based on the 80-year interval between the prior
two novae ($2026 \pm$3), the current accretion high state increases the
likelihood of a TNR occurring in T CrB in the next few years.
