king instance is often afforded by those illiterate persons who follow this pursuit. These often voluntarily abstain from studying the scientific labours of their predecessors, of which I have known instances, in order to preserve the originality of their projects, though frequently at the expense of their perfection and utility. If, then, the larger portion of the labour of these men is devoted to the attainment of celebrity, they can hardly quarrel with results of their own making, nor expect fortune to come to their hands unsought.

Persons who wish to acquire wealth, or, in fact, to achieve any permanent end, are generally obliged to use steady perseverance, and to apply all the talents they are masters of for a[328] length of time. Precisely the same is the case with inventors. That inventor meets with very extraordinary success indeed, who is not obliged, in the application of his plans to a useful purpose, to employ prudence and economy, and all those qualities which enable a man to conduct business to advantage and to influence the minds of others. Hence it is that inventions so often lie for a length of years, forgotten or neglected, till some one of less originality, but more perseverence, influence and mercantile calculation, carries them into effect with advantage.

The want of being acquainted with the efforts and discoveries of predecessors is the cause of prodigious waste of time and talent. Hence the thousand schemes for perpetual motion, and a variety of other attempts scarce less extravagant, because made with equal ignorance. And, in fact, there is a strong tendency in having acquired the knowledge of the labours of others, to clip the wings of invention, and render men of learning much less apt to attempt novelties than while they knew less.

Extravagance in pecuniary matters is another frequent cause of th