I am reminded on this very sad day of something I saw in the extras of one of the Lord of the Rings DVDs many years ago. The actor who portrayed King Theoden was talking about being dressed in the King's armour for filming - as some part of the costume was lowered over his head, he noticed carvings or motifs on the inside of the part in question.
Being on the inside, movie watchers would never see this detail. The craftsmen/women who made the armour would know about it. The actor would know about it (if he was observant enough, which he was). Some designers, the director, maybe the producer/s would know about it. But of all the people who ever saw that armour, only (literally) a handful would have been aware of, let alone have seen, the workmanship those motifs represent.
The craftsmen/women cared so much about doing their job, they did it as completely as they could, as if they were preparing the armour for a real King to whom such details would matter.
Anyone who has ever cracked open a classic Mac knows it can take some doing. Torx screws (who'd ever heard to Torx screws in 1984?!) down a long and narrow hole required a special tool and not a small amount of perseverance to remove. Apple did not design the original Macs in a way conducive to them being opened. Steve Jobs wanted a closed system, literally.
Steve Jobs recognised the original Mac team were artists and great artists sign their works. It was Steve's idea to have the signatures of the Mac team embossed on the inside of the Mac shell. Over at Folklore.org, Andy Hertzfeld recalls:
Most customers would never see them, since you needed a special tool to look inside, but we would take pride in knowing that our names were in there, even if no one else knew.
It's just a small, but very Mac retro way Steve Jobs reminds us that even invisible details matter in design, even if it's only to the designers who ever see the details.
R.I.P. Steve Jobs - we'll be discovering your invisible details in your life's works for many years to come.