RYAN, J.

Michael Delgado was tried by a jury and convicted of delivery of a controlled substance, heroin, MCLA 335.341(1)(a); MSA 18.1070(41)(1)(a). His conviction was affirmed by the Court of Appeals in an unpublished per curiam opinion. We granted leave to appeal. 399 Mich. 837 (1977).

The defendant's conviction arose out of a course of continuing conduct in which he sold a quantity of heroin to one Vincent Mazzara, a City of Detroit undercover police officer. During the course of the dealing, Delgado delivered heroin to Mazzara on two occasions, January 17 and 22, 1974. The information filed in the instant case charged defendant only with delivery of heroin on January 22. In a separate information, defendant was charged with selling an ounce of heroin to Mazzara on January 17.

Before the trial concerning the January 22 sale, which is the matter before us, the defendant's attorney moved to consolidate the two cases based upon considerations of expedience and collateral estoppel and, because, as he put it: "[it] is just one entire transaction, even though there are two different dates." The trial judge denied the motion because she believed there were two separate transactions and no "compelling factual reason or legal reason to consolidate them for trial". Testimony concerning the January 17 sale was admitted at defendant's trial on the justification that it constituted a "similar act" within the meaning of MCLA 768.27; MSA 28.1050. On appeal defendant contests the admissibility of the "similar acts" testimony; he has not contested the denial of the motion to consolidate.

The people's case is built primarily around the testimony of undercover officer Mazzara. Mazzara's testimony begins with his introduction to defendant, Delgado. A mutual acquaintance, Herbert Schpre, arranged a meeting between Mazzara and defendant in consideration of a promise that if Mazzara purchased heroin from Delgado, Schpre would receive 10% of the purchase price. At this meeting, which occurred on January 15, defendant took the position that he would sell nothing less than a quarter kilo of heroin. As the buyer, Mazzara maintained that he would first like a sample of the heroin and explained that if he liked the sample he would then buy a quarter kilo. After much discussion defendant acceded to Mazzara's terms and agreed to sell him a single ounce as a sample, as soon as the drug became available.

At the conclusion of Mazzara's direct examination, the prosecutor sought to introduce a tape recording of a January 17 telephone conversation between the witness and the defendant. The defendant objected to the admission of the tape on the ground that the judge had earlier ruled that it was not part of the same transaction and that the probative value of the evidence was outweighed by its unduly prejudicial character so as to preclude its introduction under the "similar acts" statute. Overruling defendant's challenge, the trial judge permitted the recording to be admitted under the statute.

After Mazzara testified that he had placed a telephone call at 1:30 a.m. on January 17 to defendant at the Ball Park Bar, which defendant owned, the prosecutor proceeded to play the recorded telephone conversation for the court and jury. In that conversation defendant told Mazzara to come to the bar, and Mazzara asserted that he had "got the cash and everything".

Mazzara testified that he arrived at the bar at about 2 a.m. and that defendant took him to his car in the parking area where Mazzara purchased one ounce of very dark heroin from Mexico for $1600. Mazzara told defendant that if "his people" liked the sample, he would "get back with him to possibly purchase a quarter kilo".

Mazzara's testimony continued with his description of a meeting with defendant at the Ball Park Bar at about midnight on January 22. Mazzara told defendant he wanted to buy a quarter kilo of heroin and wanted to deal directly with defendant because Schpre's percentage was too high. Defendant gave Mazzara his home phone number and told Mazzara to call him at home at around 3 a.m.

Mazzara made the 3 a.m. telephone call as instructed. A tape recording of that conversation was received as evidence without objection and played for the jury. In that conversation defendant said he had three ounces of the "same kind", but stronger, at a price of "eighteen". Mazzara agreed to meet defendant at defendant's house.

Mazzara arrived at defendant's house at about 3:30 a.m. on January 22. He purchased three ounces of dark brown Mexican heroin for $5400. Mazzara said if he liked the heroin he would call back within a day or two to buy a larger quantity.

After the close of the people's proofs, defendant rested without presenting any evidence. In closing argument, defense counsel vigorously attacked Mazzara's credibility and argued the existence of reasonable doubt.

The first issue involves the question of admissibility of evidence of defendant's January 17 sale of heroin to Mazzara.

Defendant contends that the introduction of the evidence concerning the January 17 delivery of heroin tended to show that he was guilty of a separate and distinct criminal act. Accordingly, he asserts that the recorded conversation of January 17 and the testimony relative to the alleged purchase on the 17th should not have been admitted into evidence. We disagree.

It is the nature of things that an event often does not occur singly and independently, isolated from all others, but, instead, is connected with some antecedent event from which the fact or event in question follows as an effect from a cause. When such is the case and the antecedent event incidentally involves the commission of another crime, the principle that the jury is entitled to hear the "complete story" ordinarily supports the admission of such evidence. State v Villavicencio, 95 Ariz. 199; 388 P.2d 245 (1964); People v Wardwell, 167 Cal.App.2d 560; 334 P.2d 641 (1959); McCormick on Evidence (2d ed), § 190.

Stated differently:

"Evidence of other criminal acts is admissible when so blended or connected with the crime of which defendant is accused that proof of one incidentally involves the other or explains the circumstances of the crime." State v Villavicencio, supra, at 201.

See also State v Page, 395 S.W.2d 146 (Mo, 1965); United States v McCartney, 264 F.2d 629 (CA 7, 1959); Guajardo v State, 168 Tex Crim 503; 329 S.W.2d 878 (1959); State v Kuhnley, 74 Ariz. 10; 242 P.2d 843 (1952); 1 Wigmore, Evidence (3d ed), § 218; 1 Wharton's Criminal Evidence (12th ed), § 284.

The foregoing principle is applicable to this case. An agreement for an initial sale of sample heroin and a subsequent sale of a larger quantity of heroin was reached at the January 15 meeting between Mazzara and defendant. Mazzara's testimony concerning this meeting clearly delineated an anticipated course of dealing in which the sample purchase of heroin would be made as a condition precedent to a subsequent purchase of a greater quantity of the same, if the sample proved to be of adequate quality. Mazzara's testimony to that effect was received without objection. When later in Mazzara's testimony the defendant objected to admission of the telephone recording of the 17th, which concerned the negotiations for the sample purchase, the jury had already been made aware of the fact that there had been two separate but interrelated sales of heroin. In addition, the recorded telephone conversation of the 22nd setting up the sale to be made on that date, which was received without objection, made clear reference to the prior sale. In that conversation defendant said he had three ounces of the "same kind", but "stronger" at a price of "eighteen".

The defendant's peculiar and inconsistent pattern of objection did not serve to insulate the jury from awareness of the fact that there had been a prior sale, but served only to keep from the jury the specific details of the course of dealing between the 15th and the 22nd and interrupted the continuity of the testimony relating to it.

As the recital of the facts discloses, the sale on the 17th and the sale on the 22nd were inextricably related, one to the other. Quite literally, the sale on the 22nd followed from the sale on the 17th, as does an effect follow from a cause. The jurors were entitled to have before them the facts concerning the sale of January 17 as an integral part of the events which were incidental to the January 22 sale.

In finding that the evidence was properly before the jury, we deem it unnecessary to decide whether the evidence was admissible under the "similar acts" statute and intimate no view with respect thereto.

Defendant next contends that the trial judge erred reversibly in failing to instruct that knowledge that the substance delivered was heroin is an element of the offense of delivery of a controlled substance.

We reject this claim of error. In People v Rios, 386 Mich. 172; 191 N.W.2d 297 (1971), this Court looked to the statute prohibiting the unlawful sale of narcotics in order to determine the essential elements of that offense. The statutory provision at issue in Rios was the predecessor to the "delivery" statute at issue in this case. In Rios, after reviewing the former statute, this Court held that the elements of an unlawful sale of narcotics were: "(1) the lack of license; (2) sale of a prohibited narcotic drug; (3) to another identifiable person." The former statute made no mention of knowledge of the character of the substance and this Court did not find knowledge to be an essential element of the offense. Similarly, the present statute prohibiting the unlawful delivery of a controlled substance makes no mention of knowledge. Accordingly, we cannot reasonably conclude that either the case law or the statute proscribing the delivery of heroin required the trial judge, at the time this case was tried, to instruct the jury that knowledge that the substance was heroin is a separate element of the offense of the delivery of a controlled substance.

Although neither the case law nor the statute mandates an instruction to the jury that knowledge is an essential element of the crime, better practice suggests that the instruction be given in "delivery" cases to guarantee fundamental criminal mens rea requirements. The knowledge instruction is essential, of course, in cases wherein there is reasonably raised in the evidence the issue of whether the defendant, particularly an aider and abettor, knows the nature of the substance which he is delivering.

The case before us, however, is not at all analogous to such instances. At trial, Delgado did not argue that as the alleged seller of the heroin he lacked knowledge that the substance involved was a narcotic, or that the people failed to prove his knowledge to that effect. Rather, the defendant's tactic was to attack the general credibility of police agent Mazzara. The determinative factor in the case was the credibility of Mazzara in relating the events of the alleged transaction between himself and the defendant. Essentially, the defendant's sole claim was that there was no transaction whatsoever between himself and Mazzara. Defendant did not request a specific instruction on knowledge nor did he object to the court's failure to give a knowledge instruction.

We find no reversible error in the trial judge's failure to give a knowledge instruction in this case.

Defendant's final contention is that the prosecutor's closing argument was improper in six instances. Although defendant's objection to the first of those remarks was sustained, defendant made no objection at trial to the remaining five remarks he now argues were improper. Defendant did not request a cautionary instruction, and no instruction specifically directed toward the prosecutor's argument was given. The trial judge did instruct generally that "the law, of course, does not permit jurors to be governed by sympathy, by prejudice or by public opinion", that the jury was to "consider only the evidence in the case" and that attorneys' "statements and arguments are not evidence".

Where no objection to prosecutorial argument is made below, appellate review is precluded unless failure to consider the issue would result in a miscarriage of justice. People v Duncan, 402 Mich. 1, 16; 260 N.W.2d 58 (1977) (opinion by RYAN, J.), and cases cited therein. While some of the remarks here might have been better left unsaid, the remarks were not "fatally prejudicial or entirely without provocation". People v Allen, 351 Mich. 535, 544; 88 N.W.2d 433 (1958).

Affirmed.

KAVANAGH, C.J., and LEVIN, COLEMAN, FITZGERALD, and BLAIR MOODY, JR., JJ., concurred with RYAN, J.