If you don't want to know the circumstances surrounding Sunday's entry in this slideshow, then don't read any further...
[spoiler]Sunday's quote:
Ep #302 (1967) - Julia - 'The injections take time to prepare and MUST be prepared with caution.'
From "#0301/0302: Robservations 01/04/02: Thrust & Parry"
Old House, drawing room - Barnabas is looking through the family album when Julia joins him. Your injection will be ready shortly, she informs him. One mistake could mean your life, he warns her. Julia sits across from him and notes how often he's been looking through that album.
[/spoiler]
The Robservations barely references the situation surrounding the quote. And how those circumstances fully play out are that Barnabas is in the drawing room looking at the family album. After Julia comes in and announces she'll be giving him his injection in about twenty minutes, Barnabas remarks that he was beginning to think she wasn't going to be coming out of her "little playroom" for the rest of the evening. At that Julia delivers the quote and then adds that one mistake could mean his life. However, Barnabas points out that she's wrong in that because one mistake could mean her life. And it is after that Julia studies Barnabas a bit, sits down, and then remarks that he hasn't put the album down all evening even though it isn't as though he hasn't seen it before...