"The word 'issue' is said to have a flexible meaning - it may mean 'children', or it may mean descendants of any degree. There is no hard and fast rule, and what we have to discover is the sense in which this testator has used the word in this will. He has used the word so often that we cannot help seeing his meaning. In eleven cases out of twelve we can see that he means by 'issue' simply 'children'. If, then, we find it to be clear, in eleven out of twelve cases, that in using the word 'issue' he means 'children', what is the natural inference to be drawn in the twelfth case, where he has thrown no light upon the meaning of the word? The natural conclusion is that he uses the word in the same sense in which he has used it before. That is good sense. I do not know whether it is law, or a canon of construction, but it is good sense to say that whenever in a deed, or will, or other document, you find that a word used in one part of it has some clear and definite meaning, then the presumption is that it is intended to mean the same thing where, when used in another part of the document, its meaning is not clear."