Perhaps someone has recommended that you should take time to stop and smell the roses. That's easy enough to say, but the practice of smelling roses is considerably more complicated than you might think.
First, where to sniff? You may think that the center of the rose is the best location to aim your nose, but this is not necessarily that case. A rose's scent is produced in its petals. Specifically, it is produced in the outer layer of cells covering each petal. Both sides of the petal produce scent, so there is no need to labor over which side to smell.
Secondly, what is the optimal time to smell the roses? It takes hundreds of volatile chemicals to produce a rose's scent. It's expensive for the rose to manufacture that many chemicals, so instead of constantly churning out molecules the flowers time when to release their fragrance. Some of the chemicals a rose releases are produced only in the light. Others, are produced according to an internal clock and are released at the same general time each day even if the greenhouse lights go off at the wrong time. Other factors like the age of the bloom and temperature may also affect how scented a rose can be, so watch out.
Thirdly, which rose? You may be tempted to pick a large, stunning cut rose from a nearby florist, but that would probably be a mistake. Roses bred for commercial purposes are often disappointingly unscented. Over the centuries, humans have bred roses for beauty, shape and resilience. As a consequence, we accidentally de-scented our roses. Luckily, scientists are beginning to uncover which genes were lost, so future store-bought roses may have more perfume to offer.