My recent share of a Swiss Cheese model sitting on my copy of HAZOP and HAZAN encouraged me to reacquaint myself with the wisdom of Trevor Kletz who is (quite rightly) introduced in the book as "Known throughout the process industries as a gifted communicator on safety matters".
I've got the 4th edition, but I wish the IChemE had kept the front cover the same as the 3rd edition to show Trevor's love for 'belt and braces'.
I didn't have to go far into the book to find one of his 'gems':
"Samuel Coleridge described history as a 'lantern on the stern', illuminating the hazards the ship has passed through rather than those that lie ahead.
It is better to illuminate the hazards we have passed through than not illuminate them at all, as we may pass the same way again, but we should try to see them before we meet them. HAZOP can be a lantern on the bow."
This book was published in 1999 and his next statement is as valid now as it was then:
Unfortunately we do not always learn from the hazards we have passed through...
Will we ever learn ?
We will pass the same way again and cannot afford to be misguided.