Primrose path

This phrase was coined by Shakespeare, in Hamlet, 1602. It is evidently a simple allusion to a path strewn with flowers.

Ophelia:
I shall the effect of this good lesson keep,
As watchman to my heart. But, good my brother,
Do not, as some ungracious pastors do,
Show me the steep and thorny way to heaven;
Whiles, like a puff’d and reckless libertine,
Himself the primrose path of dalliance treads,
And recks not his own rede.

Ophelia is warning her brother take his own advice and not reject the difficult and arduous path of righteousness that leads to Heaven in favour of the easy path of sin.

Shakespeare later used ‘the primrose way’, which has the same meaning, in Macbeth. This variant is hardly ever used now.