depends on what the purpose is... when my Grandma passed away, my family managed to hide it from my Dad for few month..Grandma use to live in a different city, and my Dad only communicated with her and his sister over the phone… at that time he just had a heart attack and was recovering from it.. the news about his Mom could kill him… Later, when he was ok, my family found the way to tell him very carefully about it..this brought him back to quite hard condition for a while again, but at least probably we have saved his life by actually lying to him, as he always asked how is she, and his sister had to answer that she is fine…

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“You become responsible forever for what you have tamed”. Antoine de Saint-Exupéry