Mossad's old motto was a verse from the Old Testament book Proverbs, which in the King James version of the Bible was translated as "For by wise counsel thou shalt make thy war." Victor Ostrovsky, the ex-Mossad agent, translated the motto as "By way of deception, thou shalt do war".1
What gives? The ambiguous Hebrew word, translated as "wise counsel", originally by the Greeks, and later by the King James translators, and "deception" by Ostrovsky is takhbulot - תחבולות . Takhbulot is the plural of takhbulah - תחבולה - which was translated as "wisdom" or "counsel" by the Greeks and later others who translated directly from Hebrew.2,3
On the other hand, takhbulah does mean a trick or deceptive device in Modern Hebrew. Did the meaning change? Why do Hebrew scholars translate it as wise counsel?
Hebrew and Arabic words - the languages are closely related - are normally based on a root sequence of three consonants. Consonants might be added at the beginning and end of the root sequence, and vowels are interspersed, to construct nouns, adjectives, verbs, and adverbs.
The Hebrew root sequence of takhbulah is ח ב ל
This root sequence leads to the Ancient Hebrew words:
Hebrew scholars have guessed (and guesswork is involved) that takhbulah was derived from rope, and that it was a system of ropes used on a sailboat to move the sails and so direct the boat, and by extension, wise counsel.4 It's a stretch, especially since Ancient Israel wasn't exactly a maritime society.
Another reasonable explanation begins with the verbs to ruin and destroy. Then takhbulah would be the kind of wisdom needed in warfare. This kind of knowledge would be exactly what a beleaguered, isolated people would need to survive.
Modern Hebrew words derived from ח ב ל are more in line with the modern meaning of takhbulah as a trick or ploy.
Mossad's new motto is also from Proverbs, and in its original Hebrew also contains the word takhbulot.
"Where no counsel is, the people fall: but in the multitude of counsellers there is safety."
The word "counsel" is the King James translation of takhbulot.
Mossad's own site, in discussing Rabbi Yehoshua Ibn Shuib's commentary on the verse, offers an impressively elastic definition of takhbulot: "intrigue" and "wise direction."5, happily (and interestingly) bridging the gap between the Biblical and modern definitions.
Whatever the original meaning of takbulot, it's clear that Mossad thinks it's a pretty good thing. They like it. And whatever the original meaning, Mossad is made up of Modern Hebrew speakers, who know that the Modern Hebrew meaning of takhbulot is ploys - a bag of tricks.
Let's leave these ambiguities with the thought that probably the best way of understanding what Mossad thinks is by learning what Mossad does.
1 Victor Ostrovsky and Claire Hoy, By Way of Deception (New York: St. Martin's Press, 1990), 53
2 Takhbulah in Ancient Hebrew was generally written תחבלה with plural תחבלות . In Modern Hebrew the spelling is תחבולה making the "oo" sound in the second syllable explicit.
3 See for example Strong's Hebrew Concordance . (Widely available on the internet.) Hebrew words in this dictionary are individually numbered., and takhbulah has the number 08458.
4 Francis Brown, S. Driver, and Charles Briggs, A Hebrew and English Lexicon of the Old Testament (Oxford: Clarendon Press, 1939), 287
Available here: https://en.wikisource.org/wiki/Index:A_Hebrew_and_English_Lexicon_(Brown-Driver-Briggs).djvu, Accessed 1/23/18