«As you know, no one over thirty years of age is afraid of tittle-tattle. I myself find it much less difficult to strangle a man than to fear him.»

«Before I put a sketch on paper, the whole idea is worked out mentally. In my mind I change the construction, make improvements, and even operate the device. Without ever having drawn a sketch I can give the measurements of all parts to workmen, and when completed all these parts will fit, just as certainly as though I had made the actual drawings. It is immaterial to me whether I run my machine in my mind or test it in my shop. The inventions I have conceived in this way have always worked. In thirty years there has not been a single exception. My first electric motor, the vacuum wireless light, my turbine engine and many other devices have all been developed in exactly this way.»

«A man who views the world the same at fifty as he did at twenty has wasted thirty years of his life.»

«David was thirty years old when he began to reign, and he reigned forty years.»

«As for the sons of Merari, thou shalt number them after their families, by the house of their fathers; / From thirty years old and upward even unto fifty years old shalt thou number them, every one that entereth into the service, to do the work of the tabernacle of the congregation.»

«And this I say, that the covenant, that was confirmed before of God in Christ, the law, which was four hundred and thirty years after, cannot disannul, that it should make the promise of none effect.»

«And those that were numbered of the sons of Gershon, throughout their families, and by the house of their fathers, / From thirty years old and upward even unto fifty years old, every one that entereth into the service, for the work in the tabernacle of the congregation, / Even those that were numbered of them, throughout their families, by the house of their fathers, were two thousand and six hundred and thirty.»

«And those that were numbered of the families of the sons of Merari, throughout their families, by the house of their fathers, / From thirty years old and upward even unto fifty years old, every one that entereth into the service, for the work in the tabernacle of the congregation, / Even those that were numbered of them after their families, were three thousand and two hundred.»

«But Jehoiada waxed old, and was full of days when he died; an hundred and thirty years old was he when he died.»

«A poet more than thirty years old is simply an overgrown child»