It’s critical to differentiate the Ablative of Instrument and Ablative of Agent.
- Instrument uses [ablative]; Agent uses [ab/ā + ablative]
- He perished by the sword: gladiō occīsus est.
- He was killed by the enemy: ab hoste occīsus est.
- He was vexed with a problem: curā vexātus est.
- He was haunted by the ghosts of his past: ab manibus priscīs vexātus est.
With the first example, the sword is the tool used to kill him, not the sentient agent committing the act. With the second example, the problem is the source of his worries, but the problem is not a sentient agent. The Ablative of Instrument has a sense of inanimate agency, but only the Ablative of Agent carries a sense of animate agency.
- Animals tend to sit in the seam between these two options: sometimes they are instruments, sometimes agents. Look for ā/ab! This will not only help to make the silly distinction, but also help to show the kind of agency the author is attempting to associated with the ablative construction.
For more on the Ablative of Instrument: http://wp.me/p2eimD-52
The Essential AG: 405n2; 405bn2