Archer places Dr. Phlox in control of the Enterprise when the crew requires sedation to survive a trans-dimensional disturbance. This mind-altering section of the Expanse is lethal to humanoids. But Phlox's Denobulan physiology doesn't entirely shield him from its effects, causing hallucinations. 

After pinpointing the site of the Xindi doomsday weapon, Archer plans to sacrifice himself to destroy it. Daniels arrives and takes him 400 years into the future to show him the far-reaching consequences of the Enterprise crew's actions and to beg Archer to reconsider.