The shortest track on the album (and one of the band's shortest ever) at just under 3 minutes, Vacant is a song written by singer James LaBrie about a seizure and coma suffered by his daughter at a young age. The raw emotion of a helpless parent wondering if they're losing their child is matched by the stripped-down instrumentation, with no guitar and drums but with the addition of a cello part. Bass and cello, with similar frequency ranges, match each other in some places and split apart in others, enhancing the detached, "waking dream" feeling of the song.
Cello has been charted to guitar. I briefly considered using cello tuning for pro guitar but just went with "low 6 strings of 7 string" (BEADGB) which has the nice quality of matching the bass tuning.
Guitar tuning: Low 6 strings of 7-string (B E A D G B )
Bass tuning: 5-string (B E A D G)